CA reactor and PH    8/25/09 Hello Crew, <JD> First, many thanks for maintaining such an excellent sight for reef keepers! <Welcome> I have recently installed a CA reactor that is happily keeping the CA in my tank around 450. The alkalinity is also staying in the 12 - 16 dKH range. I have noticed though, that the overall ph has been reduced to around 7.6. <Dial the CO2 back... be happy with lower CA and KH> Although this number is VERY stable with the reactor in place, I feel like it should be up around 8.2. Am I worrying about nothing here? <Worrying about something> Should I look to raise the ph value in the tank? <I would; yes> If so, what is the best way to raise the ph without increasing alkalinity? <Less carbon dioxide feed likely... though some folks get involved in feeding carbonate additionally to their reactor input> Thanks in advance from a faithful reader, Jd <Please search/see WWM re. Bob Fenner> Re: CA reactor and PH  8/25/09 Wow! What a privilege to speak directly to Mr. Fenner! :-) I just recently got a copy of your second edition book, which I enjoy very much, and lives on my coffee table. Many thanks for so many contributions. <Welcome my friend> I usually start to worry if CA goes < 400 or dKH < 10. Is this still the proper thinking? <Mmm; not really... as long as both are neither precipitously high or low, there is not much to be lost> I keep a few SPS, and some LPS in my tank. 2 250 MH lights over 130 gallon half cylinder tank. <Do see/read on WWM re biominerals, alkalinity... I'd let yours drop a bit, check on Mg proportionality... not be overly concerned with these> I will look to dial back the preferred PH of the out coming effluent from CA reactor so that I use less CO2 to keep the PH lower in the reactor. Thanks again for your advice. -Jd P.S. Attaching a pic of my tank to share with you. I couldn't have done this without your crew, and hours of reading on WWM. :-) <Ahh, very nice. Thank you for sharing, BobF>

Calcium Reactor Adjustment/Potential for Earth Element Overload – 01/23/07
Hi gang,
<<Hello Chuck>>
I just bought a Korallin 1502 calcium reactor for my reef. . .and am seeing almost immediate improvement in the health/appearance of my corals after an over-the-holidays stretch of having trouble maintaining calcium/PH.
<<Glad you found a solution to the problems>>
My questions are these:
(1) Since the aragonite media is being dissolved in pressurized-and CO2-enriched tank water, is it difficult (or preferably impossible) to create a 'snowstorm' effect as long as I don't add other tank additives which would affect alkalinity?
<<I think it unlikely as long as the reactor is not grossly oversized for the system.  In other words, if the unit was to provide calcium/alkaline material faster than the system could utilize it then there might be the potential for overload...though I can’t say I’ve ever heard of a precipitous event attributed to the calcium reactor.  But even so, these are not “install and forget” pieces of equipment.  You still need to monitor earth element/bio-mineral content and make adjustments to the reactor as necessary>>
(2) Are some of the other minerals (strontium, magnesium, etc.) which are in the media being released in bio-available form for use by the corals and other occupants of my system? (I've heard/read both 'yes' and 'no' on this.)
<<This stands to reason, yes...though content will vary with differing medias and all elements don’t have the same range/rate of solubility so who’s to say “how much” of the available elements in the media are being reintroduced.  As with alkalinity/calcium, these to need to be tested periodically and supplement as/if necessary>>
BTW, after a bit of trouble finding the right CO2 bubble rate vs. effluent drip rate for best effect on the smaller Korallin model, the tech guys at Marine Depot advised 15-20 bubbles per minute with about 60 drops of effluent. . .scaling it back a bit once the desired levels are reached.
<<Good advice this last>>
I bring it up only because it's not something that was in my owner's manual.
<<Thank you for the input>>
Chuck
<<Regards, Eric Russell>>

CA Reactors…Calculating Dissolution - 12/31/06
Good morning,
<<Hello>>
I would like to ask a question pertaining to the "Calcium Reactor without CO2? - 12/14/06" thread.
<<Ok>>
I have been considering the same thing as the original inquiry.  I have well water with a pH of 5.7-5.8 after RO/DI.
<<I see>>
I know enough chemistry to be dangerous, which is not much.  I seem to remember it would be possible to calculate the amount of Ca liberated by raising the pH from a given point to the point it will no longer react with the media.  The problem is I cannot find the equation anywhere.
Thanks
<<Hmm, don't know what that equation would be either...I'm sure Bob will chime in if he knows.  But so you know, the media will "react" at "any" pH level...it's just that at the higher pH more bicarbonate has been converted to carbonate leaving less "room" for the media to dissolve before reaching the point of saturation where the reaction stops.  According to Randy Holmes-Farley... "At a pH of 6.5, about 50 times less carbonate is present than in the same solution at pH 8.2"...  The difference here being the lower pH allows "much more calcium" to dissolve before reaching saturation.  Regards, EricR>> <There are solubility product constants... and I do believe/think that these can be calculated further for different pHs... the KOH for carbonates being? Perhaps a go with a CRC reference... or trip to a large (college) library, help at a Chemistry dept... Am out in HI, and too bushed from traveling to do much more than make these vague generalizations. RMF>

- kH and Ca question -
Greetings my lords...
<Oh please... I'm just a regular old human...>
I just want to ask a few simple questions:
1) Am I right that Calcium reactor increases kH but Kalkwasser increases Ca? <The calcium reactor is good for both Ca and kH - the Kalkwasser is good really only for the calcium.>
2) Now I'm using only Ca Rector. My kH is 8 dKH and Calcium ~ 400 mg/l. Is it ok? <I think that is fine.>
3) If not what should i do to increase kH (using only Calcium Reactor and/or Kalkwasser [i mean: not using any other solutions like KENT etc.]), if it's possible of course? <It is possible, but is it necessary - I think if you've got some calcium-greedy inhabitants, and you can keep those Ca and kH readings consistent, the system will do just fine.>
4) I'm adding water from Ca reactor with 1,5 drop / second and 0,5 bbls / second > Is it well calibrated or should i recalibrate it? <While that seems like a lot of CO2 to add, I'd say that all reactors are different and if you can keep these results consistent, you will be doing just fine. Perhaps keep your eyes on the pH of the system for stray CO2.>
Tanks for answer in simple words ;-)
Great website by-the-way <Is the result of contributions like this.>
Peter
<Cheers, J -- > 

- Calcium Reactor and Kalkwasser Slurry -
Hi...
<Greetings, JasonC here...>
I've recently added a calcium reactor, and have tweaked it to the appropriate dKH (11) and calcium (~470) that I was looking for.  As happens with reactors, though, my pH has suffered a tad - 7.8 in the morning, 8.0 in the afternoon.  I've had recommendations of using a light Kalkwasser slurry with my nighttime RO top-off, and was wondering if you had a recommendation on that, or any other additive that I could use with the top-off to help raise the pH ~0.2 or so. <I would just add buffers to the top-off and for the most part skip the Kalkwasser. Perhaps add the Kalkwasser once a week - test for calcium, don't add more than your system needs or you may precipitate the calcium.> I know that some advocate a calcium reactor as well as a Kalk reactor, but I really can't sink more money (or under-tank space) into a Kalk reactor. <I don't think the Kalkwasser reactor is necessary. You might also consider turning off the CO2 via the solenoid over night to avoid the corresponding pH drop.>
Thanks...
Arthur
<Cheers, J -- >

Calcium reactor and Kalkwasser
Hic! Good evening guys, it's 8.00pm over here on this glorious st pats day, and I've just got in from the pub with 5 pints of the best Guinness this side of Dublin firmly tucked up inside, i am sat here with my beer goggles on so if my typing goes a little astray you'll know why, after my email this morning i have tested my water parameters are as follows:
Nitrate 12mg/l SeaTest
Phosphate 0mg/l SeaTest
Nitrite 0mg?l
Ammonia 0mg/l
ph 8.08
Could I be right in thinking that the nitrate might be depressing the ph slightly and ultimately the dKH, as the dKH of the tank is 8 (German) and the effluent leaving the reactor is 19.
<Doubtful it would depress dKH/alk.  More likely to depress pH, which is only slightly depressed.>
I have only had it running like this for about 2 weeks as a lot of reefers over here like to have the dKH leaving the reactor at about 35 degrees (German) this is virtually impossible to achieve using a Knop, so I visited Bobs site on Knop reactors and altered the parameters as per his instructions (effluent about 1 litre per hour/gas about 20 bubbles per minute).  So I am hoping that in a couple more weeks the dKH will rise, if this doesn't work I was pondering purchasing a small aqua medic denitrator, my tank is chock full of Fijian live rock and I change 5 gallons every weekend, using instant ocean with r/o water (but i do not use any buffer).
<I would lower nitrates but I doubt it is depressing alk.  How about top off?  RO as well?  This may be your issue. No mention of total volume here, but top off and new water with low alk/dKH could off-set reactor while you are trying to actually elevate alk. I would aerate and test new water and ad buffer/carbonate supplement as needed to get alk/dKH in proper range.>
Lastly with regard to the Aragamite, I will still use it but can it be used in the same water as the Kalkwasser?
<I would dose separately.>
Sorry about the length of the mail but its the ramblings of a half p-----d Manchurian. Paul
<Hope you are having fun Paul. Happy St. Patrick's day! Craig>

- Calcium Reactor Question -
<Good morning, JasonC here...>
I have a K2R Calcium Reactor in my sump. I have a powerhead running it. Right now I have it set up so the powerhead and the recirculating pump are running all the time. The controller turns the CO2 off and on. I think from reading on the web site that you are supposed to turn off the pump the feed's the reactor. <Nope.> I have tried this but the reactor just back siphons into the sump. <That's why you don't want to do it.> Do you have any suggestions on how to stop the back siphoning? <Leave the pump running, turn off the CO2 with the controller like you have it now... is fine.>
Thanks a lot for your help!
<Cheers, J -- >

WWM new book and CA reactor 7/8/03
Anthony, GREAT BOOK YOU TWO, and to the rest of the contributors.  Thanks for the signed personalized copy!!   
<our pleasure... thank you!>
Do I understand it right when you say this is only the 1st in a 3 volume set?  
<quite correct... Fishes and then Cnidarians to follow>
Anywho, I have a 90 gallon reef with one maxima clam and about 10 LPS corals, and hooked up to it a Knop model C calcium reactor.  Here's my readings: tank:  Alk.-10dkh,  CA-330-340,
PH-8.1-8.2 .  
<all good except the pH is a little flat. Do consider a second media chamber on the outflow of the reactor to temper this>
Reactor readings are: Alk-17dkh,  CA-440,  PH-6.6 .  Is this reactor going to push up the calcium in  the tank ?  
<can be finessed yes... but your moderate readings if kept consistent will be better/safer for coral growth than difficult and inconsistent spikes to idealized high end extremes. No worries>
I've been running it for about 5 months and changed out the Korallith media once already.  
<good>
I thought I might be able to stop adding Kalkwasser everyday, and maybe just once or twice a week with a CA reactor but that doesn't look like its going to be the case.  
<can be... but then... Kalk still has huge benefits>
Any ideas to get some more of this CA from the reactor into the tank?  
<definitely the second reactor chamber will help>
Or is that all I might be able to get out of it?  Also I know my tank PH is a little low , any ideas on getting that up?  
<do check to see that it is not an aeration issue (accumulated CO2 in the system)>
Thinking about adding a second chamber to this reactor setup, but I don't know what to use for it, <same media if you like> or what kind of readings I would want to get for the effluent out of the second chamber (do they want to be the same as for the first? )  
<a higher pH for sure>
Maybe a simple plan on what  to use for the second chamber would be a good start for me.  And one more thing , I know I know,  I have the reactor feed off a tee from my mag. 9 , and I think I might be over-pressuring the reactor because I shut off the co2 and RA for water changes and then when I turn it back on the gas has a hard time getting out of the bubble counter without my help, (a couple power outages and I noticed that the co2 was not going in, it was just stuck in the bubble counter tube.)  Should I go to a dedicated powerhead for this supply and if so what one and size would suffice?
<hmmm... not sure the dedicated PH would do the trick... but it is a safer and more sensible strategy. I agree. Do consider adding a proper Eheim as a dedicated pump. Best regards, Anthony>

- Calcium Reactor Solenoid -
Got another question I was told that when the lights go off on the aquarium so does the calcium reactor... I was told that it stays on 24/7 ... I'm not sure need help <All depends on what is going on with your pH and how your system is setup... systems with algae refugiums tend to have more stable pH overnight so it's a safe bet to leave the calcium reactor running. If your pH takes a dive overnight, it works out better for your system to turn off the reactor with the lights so the reactor doesn't drive the pH down further. If you're not sure where to go from here, run a bunch of pH tests at many times of the day and night - if your average pH overnight is dropping below 8.0 - 8.2, run the reactor with the lights.
Cheers, J -- >

- Calcium Reactor Adjustment -
Anybody and all of WWM Crew, I have to know you're opinion on a couple calcium reactors.  I currently own a Knop C reactor and I find it very troublesome,  There is a lot of air that gets trapped at the bottom of the reactor, the effluent valve keeps clogging and I can never get it set to a constant rate, water comes in and back-fills the bubble counter when I loose power  or shut down  the solenoid valve, the calcium is at 450 at the effluent but the tank wont' go above 350, I've had it for about 7 months and I just don't really care for it. <Sounds to me like it's not adjusted properly and/or you're not using the Knop media.> As I said though my biggest concerns are the CO2 build-up at the bottom and that effluent valve that just doesn't seem to work for me. <Try increasing the effluent drip rate.> I'm wondering if any of you have used the Korallin reactor and had any problems with it, and also if anyone has any problems with the Knop S IV reactor. <I've used the Knop type C and the S-IV.> Those are the 2 reactors I'm thinking about getting, could someone tell me if one or the other is a better running one, or if one of those has had any similar problems as I have with the Knop C. <I really like the S-IV and I am aware of some of the shortcomings of the type-C [bubble-counter filling up when the CO2 is off, but I've used one for over a year without other issues - it is a fine reactor. If I were you, I'd spend a little more time trying to tweak the reactor before I ran out and bought another one. You can cause yourself the same problems with a maladjusted S-IV.>
Steer me right, thanks
<Cheers, J -- >

- Calcium Reactor & Rising pH -
Hello, I have a question that seems just the opposite of all that I have read on your site, I just set up a calcium reactor made by "My Reef Creations" it is a dual chamber reactor. The bubble count is 22 per minute and the drip rate is 3 drops per second. <Seems a little fast to me on both counts... should be about 15 bpm on the CO2 and 3 drops per two seconds on the effluent... but not a rule set in stone.> The effluent out from the second chamber is as follows: PH 7.2, alk 16 DKH and Calcium 500ppm. <These readings seem good enough.> I have been monitoring the tank parameters and alk and calcium are rising, but I have also seen the tanks PH rise daily sense the installation from 8.25 to nearly 8.5 over a weeks time. My question is will this stabilize or just keep rising? <Well, I'd like to say it would stabilize but it may not. What else is in your care regimen that you've not mentioned here - do you add Kalkwasser? Do you have an algae refugium?> The drip is going into my sump through a overflow bulkhead and is getting mixed with some air so I am thinking any excess CO2 is getting released into the atmosphere. <With a second chamber on your reactor, I doubt seriously that you have any excess CO2 at all. In fact, I would test the effluent before the second chamber... should be in the range of pH 6.5-6.7. If not, make some adjustments... it would seem in this case that you can afford your final effluent to be a slightly lower pH.> Will alkalinity from the reactor keep increasing the PH? <Not forever, but you do understand that the presence of buffers makes the maintenance of a higher pH much more easy. As I mentioned before, you should look to other things you might be doing - buffering top-off water, Kalkwasser, two-part additions as sources for a pH boost [as the most common trend in aquaria is towards a depressed pH] and stop those practices. A calcium reactor all on it's own won't raise the pH but the additional buffers along with the aforementioned practices could cause some problems.>
Thanks Mike
<Cheers, J -- >

- Calcium Reactor & Rising pH, Follow-up -
Since the reactor has been set up I stopped using Kalkwasser, I do have a refugium inline, My PH prior to the reactor never climbed that high 8.2-8.35 was the normal range. The only additives I add is iodine. I do add buffer to my water before adding salt when making water for changes, but add no buffers to tank since setting up the reactor. I will try making some adjustments to the reactor to lower the effluents PH.
<Sounds good. Let us know how it goes.>
Thanks
<Cheers, J -- >

- Calcium Reactor Tweaking -
Hi guys, Hope all is well. <It is indeed, thanks for asking.> Wondered if you would mind answering a couple of questions for me. <I can certainly try.>
I have just made a calcium reactor, partly from OZ reef Diy plans (great site), and similar projects.
After some tinkering it works a treat. The calcium level is coming out of the reactor at around 550 ppm, and the alkalinity is around 35 KH in dKH, or approx 11.50meq/L! <Egads, that is a little high... best to shoot for a dKH of about 15 to 17.>
Bubble rate is around 12-15 p/min., pH is 6.70.
Here's the problem. I have been reading up on the amount to dose the system, and I know that every tank is different, but I would really appreciate your input on the amount I should drip in to the tank.
The tank and sump is 200 litres capacity, there is 20Kg of live rock heavy coralline, and around 6-8 soft corals of different descriptions. I have estimated, although I am in the process of doing this again without adding remineralized RO  top up water, to be around 0.305 meq/L per day. Which is not a lot really I know, but as soon as I can afford good lights I plan to stock some SPS corals.
Current tank levels are 3.09 meq/L, and calcium is at 400 ppm (still working out the demand for calc at the mo)
I have had problems past of depressed pH in the main tank, and with great advise from you sourced it to poorly prepared RO water. I am therefore a little hesitant of dripping the effluent back into the tank straight from the reactor, so I have been bottling it and aerating it before dosing, which kind of gets rid of one of the benefits of not having to dose manually! <Indeed.>
So really to get to the point! I would like your opinion on what I should set the effluent drip rate at, <Three drops every two seconds should be about right, but this is different for every system... test a lot and make adjustments as necessary.> should I concentrate on keeping the alkalinity at the right level, or the calcium using the reactor). <Concentrate on alkalinity and the resulting pH in your tank - the calcium will take care of itself.> If the alkalinity is at the right level and the calcium falls, should I dose with other supplements to bring it back up, or just reduce the CO2 input& or increase effluent and do it that way. <Typically, unless your calcium demand becomes very high, you should be able to keep up with demand using just the reactor. Again... testing is the key and you don't want the pH of the effluent to be too low so be careful how much CO2 you put into the reactor.>
I know you receive many mails about this topic and I have spent many an hour going over them. <The answers were there, my friend.> I have built this reactor for a cost of 40 pounds, but don't really want to stress my tank which cost around 1000 pounds! <Just because good things bear repeating... test, and test some more... make small adjustments and then test again.> Any help/advise always greatly appreciated
Many Thanks
Rob (UK)
<Cheers, J -- >

- Calcium Reactor Tweaking -
G'day guys me again.
<Hi, Stu.>
Just a quick few questions:
Firstly I have connected my Calcium Reactor up and things are working okay. Just wanted to know how to raise the PH in the Effluent, as at the moment it is about 6.2-6.3 and from your info it seems 6.6-6.8 is ideal. <Either turn down the CO2, or increase the drip rate of the effluent.>
Secondly with a solenoid now connected to the CO2 unit and on a timer as the lights, is it okay for the calcium reactors pumps to still be operating when the solenoid is switched off with no co2 being pumped into the system. <Yes, you want this pump to be operating all the time.> And when the CO2 turns back on via the solenoid being activated in the morning will the pH, Ca and kH resume back at the same level? <After a couple of minutes, yes.> So in short term once I find the right pH, ca and kH, the unit should continue to work at that level every day? <Yes.>
Lastly after 2 years I want to remove the existing sand from the bottom of the tank and put in some new live sand. Any complications with this? <Just clouding/dusting up the entire tank, but not a big deal... will go away in a day or two.>
Thanks
Stu
<Cheers, J -- >

- Calcium Reactor and Kalkwasser -
Hi, I have a 210 gallon tank with a calcium reactor and do 38 gallon a week water changes. After aerating and adding the salt can I use Kalkwasser alone to adjust the ph in my 38 gallon replacement water mixture? <Wouldn't do this. Although the Kalkwasser will raise your pH, you're adding calcium at the same time. Could be a lot to add in one dose via the water change, if tank chemistry is right, could cause a precipitation event. Best to add Kalkwasser as a drip or in small amounts first thing in the morning.>
Thanks
Greg
<Cheers, J -- >

- Calcium Reactor Operation -
Hi Folks,
First I would like to thank you for your reply on the Paint Ball gun CO2 bottle. I did go with a standard 5 Lbs bottle and I now have my reactor bubbling away with some 4th day questions after its operation and reading as many articles as possible from your site. To begin I have a 90 gal reef Tank with mostly the light living type corals...exp: Elegance, Hammer, Fox.. etc. My water is at 7.9 ph (Low I know) hardness of about 9 DKH (Also Low). I run my outlet from my reactor to a 1/2 liter hang on holding cup with holes drilled half way up. I do this to filter sediment out and is a good place to get a test on effluent. <Sediment? There shouldn't be any.> Recently I have placed about 2 inches of Aragonite (ARM) in the bottom. I figure it can't hurt whatever CO2 is still present can work on this and kind of act like a second stage. <Ok.> My Ph levels in the effluent cup are 6.9 with a hardness that is off scale. I have a Knop C reactor with a bubble count of aprox. 24 and a effluent drip of about 1 to 1.5 drops a second.
Ok the questions.
I understand that there are 2 output variables
1) CO2 flow
2) Effluent Flow
We have 3 result factors
1) Tank Ph <Uhh... effluent pH which will affect tank pH, but must start with and consider effluent pH.>
2) Carbonate Hardness
3) Calcium
I read your FAQ's about the Marble Theory
My question if you get a high Hardness and a lower Calcium content, what do you adjust to turn it around? CO2 flow or effluent Flow? <Neither... calcium reactors are really alkalinity reactors. The main byproduct is highly alkaline water with some calcium added. If you're not getting much calcium out of the reactor, you might want to try something other than ARM, and perhaps the Knop Korallith, which is recommended for this reactor.> Or how do you increase both to correct levels with out adversely affecting the Tank Ph? <You've got to address all in concert - one reason why turning CO2 off over night is an option worth considering... won't drive down the pH over night. If you've only just gotten this reactor running on the tank, then you won't see system-wide results for a week or so... give it some time.>
If your tank is lower in pH then you still have a choice of increasing CO2 flow and decreasing the Effluent drip. <Uhh, no. For starters, don't make both adjustments at once - doing one or the other will accomplish the same result - doing both will produce the same result in much greater quantities. If you increase the production of carbonic acid in the reactor, this will drive down the pH in your main tank.>
Or would you opt to go with a lower CO2 flow and increase the effluent Drip. <This is a better option, but again - one adjustment or the other should bring you into a useful range.>
I will soon be getting a Ph controller and then this will be more like a doser, injecting CO2 to a certain lower Tank Ph and then allowing it to return to a higher Ph value as the effluent does not have the CO2 influence.
My Corals have never been happier right now even with my numbers off a bit but I am sure this must be the introduction of some CO2, for Light living types this must be like happy gas for them.
Still a bit confused... <Keep on reading.>
Thanks,
Fred
<Cheers, J -- >

- Calcium Reactor Operation -
Hi,
I recently purchased an ALS CR-500 Calcium Reactor.  Currently I supplement 1 1/2 scoops of Tropic Marin Bio-Calcium in order to keep my calcium level at 425ppm, PH 8.0-8.4.  I don't recall the alk but it was within the accepted levels.  I was wondering, when I setup my reactor and start dosing, I am assuming that I will have to stop using the Bio-Calcium.  Correct? <Yes, you should adding other calcium additives with the exception of Kalkwasser - you can add that in small amounts.>
My other concern is that I do not have a PH controller. <Not really a concern if you set up the reactor carefully, spend the time to learn its nuances.> I have read on your site where you suggest running the reactor when the lights are on so that the PH does not get too depressed. <Again... you won't know until you run the reactor on the tank, how the two work together. Not all tanks have this problem - if you have an algal sump that is lit opposite of the sump for instance, you'd have no trouble running a calcium reactor 24/7.> The manufacturer suggests a certain drip rate, but that is for the full day operation.  Am I better off running when the lights are on only? <Perhaps you misunderstood - you turn only the CO2 on and off with the lights. No need to adjust the drip rate of anything... just turn off the CO2 and the reaction will stop, the remaining carbonic acid will slowly be replaced by regular tank water due to the continual drip. Leave the reactor's circulation pump running 24/7.> Does this mean I have to increase the drip rate and effluent rate to compensate for the fact it is not running all day? <No.>
Thanks,
Jo
<Cheers, J -- >

New Calcium reactor 3/28/04
Hi gang-
<howdy!>
I just finished setting up the 265 (phew !). The 110 gal is getting broken down :( One addition to this system is the MTC calcium reactor. It too is up and running but my calcium levels are low currently (320).
<actually...they are just fine. It's more/most important to simply keep Ca levels steady. A steady 320 ppm will grow reef creatures faster than a spiking 420ppm>
DKH is 10.2 which is a little higher than I would want it ideally (9.8 or so). I have been using the B-Ionic 2 part system which I may discontinue in the new setup. My question is this. How do I boost the Ca level without risking lowering the pH ?
<you mean raising the pH I presume... and as such, temporary use of Calcium Chloride will do the trick>
It is currently 8.2 which is ideal... Last time my Ca levels got this low, I started losing some coral...
<I can assure you that was not because the Ca was low, but from other dynamics that worked in concert (business/laziness that led to overall neglect of other aspects of water quality beyond Ca supplementation>
Can I add only part 2 of the 2 component system ???
<you can... although its too expensive to make that a habit IMO <G>>
Dan
<best regards, Anthony>

Kalk - calcium hydroxide use 3/8/04
HI: I just started using Kalk in my seventy gallon reef a month ago. Until I read some of you faq's I see dosing is best at night.
<yes... a must because Kalk is caustic (high pH) and pH climbs by day and falls at night. Its the best time to dose it>
My question is do I ever stop feeding the Kalk and if so for how long.
<you must test for you daily need of calcium (test kits) and then calculate how must Kalk (or any calcium supplement) is needed to meet that need.>
If I bring in my water for testing and I an told the pH and alk is ok do I still dose.
<this is not about pH, my friend, although Kalk does help to support pH and alkalinity. It is a calcium supplement and is to be dosed and finessed as such>
I use purified water when I dose, I was told never to add tap water to a salt tank. What do you advise?
<purified water should be aerated for 24 hrs in advance to increase the pH and then it likely should be buffered before salting or using it for evap top off. Leave plain if its for Kalk use though. It sounds like you really need to buy and read a good book on reef husbandry my friend. Seek Paletta's "New Marine Aquarium" for marine basics... and read the first half of my "Book of Coral Propagation" for reef keeping coverage.
Thank You, Richard Levine
<kindly, Anthony Calfo>

- To Add the Reactor, Or Not -  
Folks,
Having saved my pennies long and hard I was about to buy a calcium reactor, prior to adding clams and some LPS to my 5 x 2 x 2. However testing has shown that my current DKH and calcium levels are bad. DKH at about 6, calcium at 280. I suspect that if I add a reactor now it might make things worse... <Why would it do that?> should I try to get a better balance before I add one. <I wouldn't - the calcium reactor will bring things into line over time - just don't rush.> How would you recommend I go about it... currently trying 25% a week water changes. <Go ahead with the reactor - let it run for a month or so an test your calcium then.>
Thanks
Brian
<Cheers, J -- >

Kalk and  calcium reactor combo? OK!
Bob, I am currently running a 500 gallon reef tank with mostly SPS.  Due to some algae outbreak I have recently added Kalk through a night drip method.
<OK... I agree with the night dosing of Kalk... but wonder why the direct correlation with algae outbreak and lack of it? Ultimately I agree that it may help as high pH and the precip of Calcium phosphate by Kalk is indirectly helpful... but a nuisance algae outbreak requires address of the nutrients causing it (need for better nutrient export: cleaner source water, better skimming/daily, etc)>
It seems as if some of the coralline has recently turned white.
<the coralline bleaching can be caused by many things... change in light from new lamps or a sudden use of carbon, water change, exposure to light in air (water change left algae high and dry under baking lights), skewed Ca/ALK dynamic (one high one low)>
Is this combo a long term problem in the works.
<not at all... Daniel Knop himself has suggested that Kalk can compliment a Knop reactor. I agree... but Bob doesn't think it is necessary. The advantage of using Kalk with the reactor is that Kalk will indirectly support alkalinity while providing calcium. The reactor is mainly boosting ALK and with the redundancy of both the system is likely to be more stable if you test and tweak regularly/as necessary. Again, I see no problem. Kalk has advantages over reactors too... besides saponification (enhancing protein skimming)... Kalkwasser is self-cleansing: almost all impurities in Kalk prec out in the high pH solution (like copper and other metals)... however, the media in a calcium reactor simply dissolves and bleeds those impurities into your system. Hence, a bad media for the reactor can contribute to a nuisance algae bloom.>
Would appreciate any thoughts on the matter.  Thanks  Terry   Using a Knop reactor at all times and night drip of Kalk.
<I use a Knop reactor myself. Love it. Best regards, Anthony Calfo>

Calcium Reactor
Gentlemen, I have a calcium reactor and have some basic questions. The two components that you can change are the bubble count and the outflow. What are the ramifications of each? Does a higher bubble count increase alkalinity, a higher outflow or does both?
<Increasing the bubble count adds more CO2 to the reactor, lows the pH, and increases the amount of material dissolved. Slowly the reactor effluent increases the contact time of the water in the media and also increases the amount of material dissolved.>
Likewise reducing the bubble count and outflow would have what effect? Second, if your sand been becomes depleted and/or is lower in some areas, is it better to replace it with additional live sand from a store or just gradually build it up with the Caribbean Beach Play sand out of the bag?
<It is best to do both. You can build up the majority of the depth with dead, dry sand, but it is beneficial to periodically add some more live sand or detritivore/sand bed recharge kits to increase and diversify the population of the critters.>
Does it matter? Thanks in advance.
<You are welcome. -Steven Pro>

- Retrofit Calcium Reactor -
Dear Crew
<Greetings Jim, Jason here...>
I have a 130 Gallon reef tank with various species of Stony Corals in it.
These include :-
2 colonies of trumpet coral
1 Faviid
1 Euphyllia
Halimeda calcareous Caulerpa
various leathers
I will possibly be adding a Trachyphylliid brain in the new year. I have managed the stock I have in currently with calcium, and alkalinity supplements; but i am thinking of adding a calcium reactor to remove the need to keep throwing in these buffers as they are quite costly. <I'm sure if you added it up, you could have purchased the reactor already.>
I will be using an old aqua-medic De-nitrifying unit as the main unit (a device in my opinion that no-one should ever need, it leeched hydrogen sulphide into my tank originally; no offence to aqua-medic or their products). First of all is this retro fit ok? <I'm not familiar with this exact unit, but unless it seals air-tight, I wouldn't do it.> My LFS says all that is required is to buy a C02 dosing kit with a solenoid and bubble counter and fill it with the required media. <A CO2 dosing kit? That's not going to provide sufficient CO2 for a reactor - I think you would find yourself spending as much on dosing kits as you were on two-part additives. Best to purchase a CO2 tank and regulator to go along with that bubble counter.> Second of all will it leech Hydrogen sulphide into the tank as it did when it was a De-nitrifier? <It shouldn't unless you are using something other than a calcium-based media in the reactor.>
My water parameters are
calcium 380
alkalinity 8.2
PH 8.4
Lastly, do these units require lots of maintenance? <Not really.> I know you have to shake the media etc, and change it every 6 months. Is that about it? <For the most part, yes... perhaps check the effluent valve/fitting to make sure your drip rates stay constant - sometimes they slow down, which would affect the dKH and pH of the effluent.> I've also read that to stop C02 leakage into the tank you can get the effluent to drip into the outflow of the skimmer is this correct? <That is correct, but it's better to determine that you are even having the problem first. Most modern reactors, adjusted correctly, consume most of the CO2 in the reaction process. Any additional CO2 will most likely be blown out by skimmers and overflows. It is typically not a concern, but if you are worried, just test first.>
cheers
Jim Griffin
<Cheers, J -- >

Re calcium reactor
Dear all
<Greetings, Jim, JasonC again.>
Just as a reply to my e-mail sent yesterday. The De-nitrifying unit by aqua-medic is totally air tight and has a slow pump within it to circulate the media. The C02 doser I was on about is in-fact as you correctly state a gas bottle with a solenoid and bubble counter. <Ah, good one on the CO2 bottle, although I would just quickly point out that a penny saved is sometimes two pennies spent later on. I'm still not completely sold on the idea of using this unit as a calcium reactor - but still... good luck.>
I will proceed ahead with the conversion of the unit to a calcium reactor. I currently have a very large profusion of purple calcareous algae (its even plating in some places). Will the calcium reactor make this algae growth go out of control? <Properly adjusted, it will certainly boost their production.> Should i scrape it all off my tank back and sides? <Only if it annoys you.>
My dKH is currently 8.4, and I'm worried if the reactor pushes this to 12 or 13 that the calcareous algae population will explode.
<Nothing to be afraid of, just may need to step up the glass cleaning. No harm is done by coralline growth.> Also as an aside, I was wondering if you could tell me whether my tank is over stocked, the tank is 110 gallons (including displacement for live rock). The tank has become more 'reef' in the last six months or so, with the addition of corals (leathers and stonies). I have :
1 Hippo tang
1 Flame angel
1 Midas blenny
1 Banggai cardinal
1 pyjama wrasse
1 sand sifter goby
1 maroon clown
1 tiny red eye goby (1 inch long)
I am thinking of removing the hippo tang (as he is large) and maybe the wrasse. <Doesn't seem crowded to me...>
cheers, Jim Griffin
<Cheers, J -- >

Calc Reactor Q's
Hello Jason,
<And hello to you.>
I've read part of your FAQ about CalcReactor and it was very helpful. <Ah good, glad it was useful for you.> Maybe I can ask you some other question... When I want to buy e.g.. AquaMedic
CalcReactor should I buy any other equipment (ph Computer or Sth)? <And perhaps a CO2 bottle and regulator. I don't think the pH "computer" or controller is necessary but because you will need to measure pH quite a bit at the onset, a digital pH probe will save you a lot of time.>
And the second one: are soft corals need Ca to live? <Not to the extent that stony corals and clams do, but most all soft corals contain sclerites, small slivers of calcium which help them form and maintain their various shapes. Free calcium is needed to form these sclerites, but certainly not in the quantities needed for stony corals.>
Thank for answer <You are welcome.>
P.S. I saw that you have probably Polish surname. I'm living in Poland and if you want you can answer me in Polish. <I'm afraid that my Polish is non-existent, and many generations removed. Sorry.>
Bye, Piotr
<Cheers, J -- >

Calcium Reactor affects on tank alk/Ca level
Dear WetWeb Crew:
<Greetings, Kevin, JasonC here...>>
Once again I need your experience in answering a question I have; your previous responses to my past questions have always resulted in success for me with my 2 yr. old 100 gallon reef tank.
After several months of non-use, I have started to again use my Korallin Kalkreactor with a 75%/25% blend of Korallith and CaribSea reactor media; prior to restarting the reactor, I was using 2 tsp of Kalkwasser/1 gallon distilled water to maintain alkalinity and calcium, but with the reactor running, I have decreased the amount of Kalkwasser I added to the distilled water to 1 tsp.  I also do a 10 gallon water change every week. After 2 weeks of running the reactor I was hoping you can help me with some questions regarding the properties I have measured.
Tank water:
Alkalinity - 4.2 meq or 11.8 dKH
Calcium ­ 320 - 330 ppm
Reactor effluent (drips into sump water over a submerged Aqua C skimmer Rio 2500 pump):
Alkalinity ­ 13.8 meq or 38.7 dKH
Calcium ­ 480 ­ 490 ppm
I mentioned that the reactor effluent drips into the sump into water that is over my skimmers pump; I do this to insure that any excess dissolved carbon dioxide is pulled into the skimmer and vented off by the agitation. Tank pH is 8.3.
After always reading that tank level calcium needs to be maintained 400 ppm or higher, I was concerned that my calcium level in my tank was to low, but since using the reactor my Tridacna derasa and squamosa are showing increased shell growth, my just added Caulastrea coral is plump and extends feeding tentacles at night, coralline algae is covering all the rocks and has to removed from the sides and front tank glass regularly, small polyp corals that had disappeared prior to the use of the reactor have started to show themselves again and the fish continue to be active and feeding aggressively (even my powder blue tang). The only possibly negative change is my two Sarcophytons do not extend their polyps as fully as they did prior
to the reactor, but the main body of each becomes fully erect once the lights come on in the morning and both Sarcophytons are getting larger, taller, and plump.
My question (sorry for the long introduction!) is am I worrying to much about my tanks calcium level vs. what is said in popular literature and in reality, based on the reaction of the tank inhabitants, is everything in good stasis. <I would say yes. If you had the opportunity to go and measure dKH and calcium levels around the world, you would be hard pressed to find the high numbers which people tell us we need. There is balance somewhere in the middle as evidenced by the growth of your clams and coralline algae. I know that high alkalinity: I calcium are mutually exclusive, but why is the reactor effluent calcium level not affecting the tank calcium level as much as the reactor effluent alkalinity level is affecting the tank alkalinity level? <My thinking here is that the effluent dKH is too high. You need this to be in the range of 15-ish. Anything higher will make it difficult for the calcium to go into solution, and more likely will precipitate out, forming deposits on the effluent valve and elsewhere. Do recall that the enhanced alkalinity brought about by the reactor will cause the calcium in your sandbed and live rock to add to available calcium. I would try just a little less CO2, and continue with the same drip rate. Ideally, you want the effluent to be at about 15 dKH and the pH to be about 7.6> Is it that the calcium level in the tank is being used up at a greater rate then the alkalinity? <That is a factor, but I'd try lowering the dKH of the effluent first - much easier to affect changes here.>
Any input you can supply on this would be much appreciated. Thank you in advance. Kevin
<Cheers, J -- >

- Calcium Reactor Question -
And hello to all those in the know! <Greetings, JasonC here...> I haven't even set up the tank yet...135 gal. Obviously this will be a reef tank and to start it off I will have 135lbs of rock in it to cycle.  From there I assume it will just be a mix of fish, and many different corals. <Uhh... don't assume - plan.> Since I will be cycling the tank with the rock, when should I be setting up the reactor? <Depends... I wouldn't bother until you have stony corals or clams to worry about - the fish don't really need calcium. I will reiterate, because I think it's important - do formulate a plan for all this, don't make assumptions unless you have money to throw away.> Do I set the thing up when I set up the tank and run it while cycling the tank, wait to cycle then hook it up? <Don't bother with it during the cycle - if this is your first marine tank ever, then your hands will be full getting the tank through the cycle.> And how do I go about setting the rate? <Start by reading the directions that come with the reactor - they are all different, but if that fails, read this article and use it as a guide:
http://www.wetwebmedia.com/calcreactors.htm >
Do I just monitor and let that be a guide assuming that I will only be using a small amount since I will only have rock to start? After getting redeye from surfing for info, I guess the consensus is to set up the reactor when everything is in balance. <That is correct.> So, would it be fair to say that soon after cycling I should fire up the reactor and continue on from there? <I wouldn't bother until you've got something in the tank that has high demands for calcium, and I would predict that is several months away if you do it right.> Eventually I feel the tank will be loaded with coral and will need the reactor. <Eventually, sure.> OR should I just go with dosing from a jug o' calcium until I get more corals in the tank? <Now you're thinking...>
Man, that was a lot of text for the simple answer I know is forthcoming!   
Thanks again buds!
<Cheers, J -- >

- Alternatives to CO2 bottles -
Hello there, <Hi, JasonC here...>
I was reading several sites that describe a DIY CO2 injector (basically for freshwater plants). I was wondering if it is possible to use this method in conjunction with a DIY Ca Reactor. I know that a downside would be weekly addition of yeast in the CO2 reactor to create CO2. But is this a possible alternative to using an expensive CO2 tank??? <Not typically. The amount of CO2 needed for a freshwater, planted tank is not as high as required for a CO2 reactor. Practically speaking, you can pick up a 10lb bottle of CO2 from a local tank supply - when I lived in Western Massachusetts, it was Miriam-Graves - for roughly $100, filled. You end up owning the tank and refills are less than $10. I ran my reactors for almost a year and never emptied the bottle. So really... over the long haul, they aren't that expensive. I really wouldn't recommend a DIY project to supplant a CO2 bottle for a calcium reactor.>
-Randy M. Yniguez, MA
<Cheers, J -- >

Calcium reactor and aquarium pH
Dear Mr. Fenner, 
I have gone through the FAQ's of wetwebmedia and could not find and answer to my specific problem.
<Okay... not surprising... many lifetimes more material to be placed> 
I have a 75 gal reef with LPS, soft, and a SPS coral and a few fish and other inverts. I installed a Korallin 1501 calcium reactor a few months ago. With a rate of 16 bubbles per minute and a effluent rate of 40 drops/min my effluent pH is 6.35 and my tank has stabilized with an alkalinity of 3.28-3.35 and calcium 420. My pH has lowered however and runs at 8.15 during the day and reaches a low of 7.89 at night (previously it was 8.3 during the day). I have noticed that my tank substrate aragonite) has been dissolving and I have recently replaced several pounds of it. I am not using any other Ca/alkalinity additives. The animals seem to be doing well and growing.
<The most important criterion>
Do I need to worry about the pH and its swings?
<Not much... would be nice, better if feeder stock melted more readily... all else being equal... and pH was higher, in-tank substrate not going away so quickly...>
Should I try to push up my alkalinity and if so how? Will increasing bubble & effluent rate further depress the pH? Should I use some sort of additive?
<I would first try simple additions of baking soda... a teaspoon per ten gallons... about once a week, blended in with system water, poured about the surface>
Want do you recommend for Ca reactor substrate? I am using Super Calc Gold now and previously Korallith with similar results?
<Would keep experimenting... your reactor may improve by some tweaking... are you able to show, accumulate some gas in the upper part of the contact chamber? Perhaps by tilting the unit? Mmm, there are better designs.>
Thank you for your response. Your web site has been extremely helpful for the last few years since I started reef keeping.
<Ah, glad to hear my efforts are of service. Bob Fenner>
Sean

New Calcium Reactor
Bob,
<You reached Steven Pro today.>
I just set up a MARS DIY calcium reactor with a Ph controller. It's been up for 48 hours and my KH has shot up to 15. 13 yesterday 15 today. The calcium has always been low, less than 300, and does not seem to be climbing like I was hoping it should/would. The controller starts the CO2 at a Ph of 6.60, inside the reactor, and brings it down to 6.35 before shutting off. Will the calcium and KH come into line over time with the reactor or should I give it some additive assistance? And, how are the proper levels maintained with the reactor?
<It is best to have your alkalinity and calcium levels at the proper levels or in the proper proportions to one another and then maintain them with the calcium reactor.>
What would you recommend for the settings on the controller? The tank is 135 gal, lightly stocked with a drip rate of 2gph from the reactor. 
<You are going to have to play around with the reactor settings and closely monitor the pH, calcium, and alkalinity until you have everything properly adjusted. -Steven Pro>
As always any assistance is appreciated. Thanks, Jim

Ph/alkalinity
Hello & (Thank You!) to the tag team answering Bobs fish tank e-mail questions, many of us greatly appreciate this effort.
<Appreciate it... hehe, we're grateful that folks are tolerating it <smile>. Seriously...thank you. Anthony>
My question is about Ph. I started running a calcium reactor about 8 weeks ago and had the effluent ph set at 6.8 (after reading Bobs faq's on this topic). My tank ph always hovered around 8.2, never below 8.0 or above 8.25.
<indeed... a nice piece of equipment and your pH needed to be a bit higher>
I'm still wondering, after reading the stored FAQs on this topic, how I can raise the ph to be in a more acceptable level. My dKH now, after refilling the reactor with Carib sea ARM and some old coral skeletons on top is 20 dKH in the tank.
<whoa!!! Please retest your alkalinity with another test kit. You are in a very dire straight (no... not the band Dire Straights, although now I have "Sultans of Swing" in my head which is not likely to leave anytime soon) if this is even accurate! Natural seawater is 6-7 dKH, but most reefs fare better at 7-10 dKH (Sprung/Delbeek) and SPS dominant tanks can even be a bit higher (towards 12 dKH). You are in serious risk of precipitating free calcium from the severe imbalance of carbonate in your system (like a reverse snowstorm from the common crystalline carbonate precipitation from Kalkwasser abuse). If this happens, you just might kill most of the living creatures in your tank within 24 hours of a precipitous event. But do not make a knee jerk reaction either... back off of the reactor (what is your bubble count on the effluent?) and do some small but frequent water changes until you get down towards 12 dKH. It isn't easy to maintain high free calcium concurrently, but at nearly 400 ppm you have managed to do so and are at great risk for it> 
I've slowed the drip rate from the reactor to bring this high dKH down. 
<brother...this has to be monitored closely from go for the first couple of weeks until you get it tweaked>
Calcium by the way is at 396. Before the Calc. reactor the DKH was always around 14 but the ph was 8.0-8.2.
<agreed...something had to be done with the pH>
The tank has been up and running 6 months and the specs are; 110 gal with 30 gals in the sump. The main tank has about 115 lbs of live rock and about 2" of aragonite "sea floor" from Carib sea. 
<see other posts or write back but a 2" substrate is problematic in the long run... not deep enough for anoxic activity (denitrification) but too deep for aerobic activity. The rule is 1/2 inch or less or three inches or more... never in between>
In the sump I have ~ 30 gals of water with ~ 15 lbs live rock, 20 lbs of a pre packaged live sand and 3lbs of Red Gracilaria,) "Tang Heaven" algae.
<cool>
I run a Turbo flotor 1000 Multi and inject ozone for an ORP in the main tank of 340 - 400. 
<nice...and reasonable>
I change 5 gals of water every week that is aged using RO water and Tropic Marin salt mix.
<hmmmm perhaps the source of your original low pH problems: did you aerate the R/O water for 12-24 hours before buffering it (mixed completely) and then later salting it. If not, you wasted buffers in the salt mix by not off-gassing or neutralizing carbonic acid from R/O water... and your 2" sand bed is hardly a significant buffer>
I add 10mg of Seachem iodide every other day
<very good>
The livestock in the tank is; 2 juvenile false perc clowns, 2 fire fish, 2 juvenile Heniochus, 1 juvenile Hippo tang (2"), 1 yellow tang(2"), 1 small bubble tip Anenome, 1 serpent star, 1 long spined urchin and 2 nice sized corals; elegance and hammer. with 3 small frags of Acro.
The water parameters are: ammon=0, nitrite=0, nitrate is non detectable using Fastest, 0 phosphates, dKH =20, Calcium= 396, Temp 77 degrees.
<I'm not a high temp fan... but you could come up a bit higher...78-82F>
I feel as though the alkalinity is sufficient enough to hold my ph to a desired level but getting it the desired level is the problem for me.
<yes...above comments>
I always feel I'm too generous with the food but the fish go nuts, acting as though they are starving to death. Only one looks thin, a "heiney" but not sickly.
<honestly...feed small portions freq and as much as you can without causing nuisance algae and nitrates>
the poly filter I have around the over flow pipe shows no sign of excess food and is changed weekly. Sorry for the length of this e-mail but I wanted to give you the full picture so you be well informed before offering your much respected advice. Any help would be greatly appreciated.
<you have your work cut out for you, my friend. Anthony>

And Steve's Reply to the above question...
Hello & (Thank You!) to the tag team answering Bobs fish tank e-mail questions, many of us greatly appreciate this effort.
My question is about Ph. I started running a calcium reactor about 8 weeks ago and had the effluent ph set at 6.8 (after reading Bobs faq's on this topic). My tank ph always hovered around 8.2, never below 8.0 or above 8.25. I'm still wondering, after reading the stored FAQs on this topic, how I can raise the ph to be in a more acceptable level. My dKH now, after refilling the reactor with Carib sea ARM and some old coral skeletons on top is 20 dKH in the tank.
<This is pretty high, about twice as high as it should be.>
I've slowed the drip rate from the reactor to bring this high dKH down. Calcium by the way is at 396. Before the Calc. reactor the DKH was always around 14 but the ph was 8.0-8.2.
The tank has been up and running 6 months and the specs are; 110 gal with 30 gals in the sump. The main tank has about 115 lbs of live rock and about 2" of aragonite "sea floor" from Carib sea. In the sump I have ~ 30 gals of water with ~ 15 lbs live rock, 20 lbs of a pre packaged live sand and 3lbs of Red Gracilaria,) "Tang Heaven" algae. I run a Turbo flotor 1000 Multi and inject ozone for an ORP in the main tank of 340 - 400. I change 5 gals of water every week that is aged using RO water and Tropic Marin salt mix. I add 10mg of Seachem iodide every other day
The livestock in the tank is; 2 juvenile false perc clowns, 2 fire fish, 2 juvenile Heniochus, 1 juvenile Hippo tang (2"), 1 yellow tang(2"), 1 small bubble tip Anenome, 1 serpent star, 1 long spined urchin and 2 nice sized corals; elegance and hammer. with 3 small frags of Acro.
The water parameters are: ammon=0, nitrite=0, nitrate is non detectable using Fastest, 0 phosphates, dKH =20, Calcium= 396, Temp 77 degrees.
I feel as though the alkalinity is sufficient enough to hold my ph to a desired level but getting it the desired level is the problem for me.
I always feel I'm too generous with the food but the fish go nuts, acting as though they are starving to death. Only one looks thin, a "heiney" but not sickly. the poly filter I have around the over flow pipe shows no sign of excess food and is changed weekly. Sorry for the length of this e-mail but I wanted to give you the full picture so you be well informed before offering your much respected advice. Any help would be greatly appreciated.
<It is not unusual for people to experience lower pH levels when using calcium reactors due to excess carbon dioxide in the display tank. Dial your reactor back to allow your alkalinity to come down to an acceptable level. At the same time, add calcium only products to keep your calcium level when it is. You are going to have to monitor your conditions closely. Once you have both where you want them, slowly increase the CO2 to maintain these levels. Hopefully, then you will no longer have excess CO2 in your display. Also, look up the excellent writings of Craig Bingman on the topics of calcium, alkalinity, reactors, and Kalkwasser. -Steven Pro>

Calcium Reactor Supplementation?
hey bob,
still fiddling around with my calc reactor; random, perhaps silly question. if ph only below 7 is acidic, above 7 is basic, does that mean the effluent ph has to be below 7 to be dissolving the media in the calc reactor?
<Mmm, actually no... the pH only needs be below the pH of the substrate being "melted"... However, I believe what you may be asking is best responded to as: there is an ideal pH for rates of dissolution that doesn't waste CO2, provides about right resultant pH, alkalinity, biomineral content...>
i have an AquaMedic, and would like to keep my effluent closer to 7-7.1, so that my ph is higher than just 7.9-8.0. will i still get substantial benefits at this effluent ph?
<Yes... as you will find>
thanks. (FYI: I'm still using the hydrocarbonate included with the unit).
thanks!
Javier
<A good idea... I would use some Kalkwasser (calcium hydroxide) and calcium chloride in most applications/types of set-ups as well. Bob Fenner>

Calcium Reactor
Dear Bob & Co.,
In my quest for the ultimate 135 gal Reef system I have decided to upgrade my hardware to include a calcium reactor. However as we hobbyists know, cost can spin out of control. To save money I bought an unused reactor that looks to be a K2R knock-off (DIY). In a side by side comparison, physically they look exact. To compliment the reactor I purchased a Pinpoint Ph controller, a M-3 regulator with solenoid, and a 5lb CO2 canister. My problem is that with the purchase of the reactor, I am without manuals. After reading your Q&A sections on CRs, I quickly learned that the CO2 bubble rate should drop the PH of the water in the reactor to 6.8, while keeping a PH of above 8.0 in the main tank...My question is with the use of the solenoid and controller. Assuming I adjust my bubble rate to reach this 6.8 PH value in the reactor, then put the monitor in the sump to measure the display tank PH. Do I set the PH controller to shut off the solenoid when the tank PH drops below 8?
<Could, yes>
Do I control tank PH through the flow rate from the reactor? 
<In a manner of speaking, yes... Please see below>
I'm a little confused regarding parameters and how to control them using the reactor, solenoid and PH controller. Do I plug the solenoid into the high limit or low limit on the controller? Can you please enlighten me?
<You could. Best to go very slow here... in establishing the use of your reactor and system together. DO keep a log book of your initial chemical measures (esp. pH, calcium and alkalinity), your adjustments to your drip rate, pH of effluent, bubble-counter... And determine what's "about right" per your gear, the reactant (media you're melting down), and biota. You will soon know what works here. Bob Fenner>
Sincerely,
Dennis

pH and Lime Reactor, second chamber
Hi WWM Crew
I had problem of low Ph, I had the same problem I been using K2R and added another canister of K2R with CaribSea aragonite to hopefully
increase my PH to 8.1 but it has been 7.8-8.0, ideally the PH should be 8.2-8.4 am I correct. 
<agreed or even a whisker higher>
Recently I also been adding Kalkwasser to the fresh water for evaporation, but has not change, LFS recommends adding super DKH to increase PH, I'm afraid it might messed up the Ca/Alk biomineralization.
<partly agreed, although I like using Kalkwasser with the reactor...many benefits to it>
I don't think I'm over injecting CO2 since it has been at 3psi, which the manufacturer recommendation, effluent output is at 6.8 of PH, DKH is 3.5, Ca at 450 ppm, oxygen saturation at 420, could this be an indication of not injecting enough co2 to increase PH, but DKH/Ca is fine and don't want to make it worst. My SPS are flourishing fine. Bi-weekly water change of 15%.
<no worries my friend... a very simple and incredibly effective solution lies in adding a second inline chamber of Aragonitic material after the primary reactor. Does wonders for the systems and will probably temper the weak pH you are experiencing. Not hard to DIY either...many plans on the net abroad. Best regards, Anthony>

Calcium reactor output
Dear Crew, The first thing to do is thank you for such an informative site, I've spent many hours getting good information. Here's my question, I run a 65 imperial gallon reef tank, overflowing with Fijian live rock, good skimming with metal halides and marine actinics, I have a good mixture of hard and soft corals along with dwarf angels and 1 Flagfin all of the tank readings are good, ph at 8.2 during photoperiod ammonia and nitrate are 0, phosphate at 0, I use ROWAphos in an external canister filter to capture phosphates which then feeds through a UV sterilizer before going into my chiller unit, water temp is constant at 78f, I use ozone in my skimmer which is controlled to give Redox at 350 I also have a Knop model c reactor which I fill with CaribSea arm media, (great stuff) I changed the media about 6 weeks ago since then I can't get the dKH to go above 7degrees (German) and the calcium is at 370, prior to this media change I was running at dKH 11.2 and calcium was at 470, my co2 bubble count is 13 a minute and effluent is at 6 drops per minute, the CaribSea packing states that a reactor ph of 7.5 is sufficient whereas the Knop site states that a reactor ph of 6.5 will give the best results, any ideas guys? Many thanks Paul
<Sounds like a very nice system... I encourage you to either experiment with lowering the pH effluent to about 6.8 or going back or switching reactor media to return to higher dKH and calcium concentrations. I do want to admit to the fact that my wife (Diana) distributes Knop Products in North America. Bob Fenner>

Calcium Reactor Questions
Sorry to bother you again today, promise my last question. 
<no worries>
A friend of mine is upgrading his Reef to a nice 180+. he is going with a calcium reactor, and has peaked my interest. I read your site but have a question. He has been told that even with a calcium reactor he will still need to drip Kalkwasser. 
<arguable, but I personally agree that there is great benefits to this>
I thought the whole point of getting the reactor was to be able to stop this time consuming practice. 
<nope... but that is a common misconception among American aquarists. Europeans have known/promoted Calc Reactors as Alkalinity boosters (carbonates) not calcium boosters, although they do some of both. Even Daniel Knop of Knop reactors has said that Kalkwasser supplementation is helpful to reactors (among other things, it indirectly supports alkalinity while providing free calcium). And Kalkwasser is not time-consuming at all.. you just haven't been shown an effective application. Please do review my comments in the WWM archives on dosing with Kalk slurries (easy mix with cold water, dosed at night in one fast shot at measures that spike pH not more than .1-.2 This was detailed at length in my book as well http://www.wetwebmedia.com/bkcoralprop.htm>
What are your thoughts. I guess one more question should we go with single or dual chamber reactors. Our feeling is the dual systems are more efficient. 
<The duals are MUCH more efficient and I strongly recommend that second chamber for pH stability among other things.>
Thanks Larry
<best regards, Anthony Calfo>

Calcium Reactor Valve
Hi Bob,
<You got JasonC this time, howdy...>
I have a K2R Calcium Reactor that is currently being fed from my main display tank via gravity flow. The effluent from the reactor flows into my sump, again, via gravity flow through a 5/8" vinyl tube.
<ok>
The effluent recommendation from the manufacturer is around 100 ml/minute for my 300 gallon display tank. <A quick word here... these should both be adjusted for your system - is different for everyone. Use the manufacturer's suggestions as a baseline and test very frequently.> However, when I set the output valve to give me this flow, it works for a few days and continues to clog. The flow stops completely and requires that I open the valve fully and then reset the flow rate every few days. <Not an uncommon problem at all, so much so that I need to check the very same valve on this morning's maintenance march.>
Originally, I fed the calcium reactor from a tee off of a small powerhead submerged at the top of my main tank, but this small amount of extra water flow caused the water to go right through the reactor (as opposed to being recirculated in the reactor via the reactor's circ pump...) <That doesn't sound correct at all - perhaps a design flaw in the K2R? Water shouldn't be able to flow out any faster than permitted by the outflow valve. Everything in the reactor should continue to recirculate.> Because of this, I needed to adjust the CO2 such that the output effluent was around 6.5 in order to get my alkalinity up to 400. This achieved the correct alkalinity but caused excess CO2 in the main tank followed by hair and other algae problems. <This can be addressed by letting the effluent run out into your skimmer... the foam fractionation process will blow out the excess CO2.>
Is there a better way to plumb, place, adjust or feed the calcium reactor that would cut down on output valve clogs and maintain the correct flow rate? <Hmmm... is a good question. I've tried them all, and I prefer a dedicated pump over a T-fitting in the return pump over a siphon feed. That being said, I just received a new Knop reactor who's tubing is set up specifically for a siphon. In addition, there are problems with T-fittings regarding line pressure. So... I'd say that each solution depends most on your installation and manufacturer. I'm going to try the siphon on this new reactor because the manufacturer is recommending that I do it this way. I would suggest you do the same unless it just isn't working at all. As for the clogging of the effluent valve, several online retailers carry an external pinch valve which will accomplish the same task, but won't get clogged by accumulating salts. You might want to give that a try.>
Thanks!
Charles T. Spyropulos
<Cheers, J -- >

Re: Calcium Reactor
Yes, I've read the CalcFAQ on WWM.. . . quite a few times actually, quite long and looks to be an oft discussed topic :-). <OK.>
Anyhow, I'm familiar enough with the concepts of the calc reactor. Just not sure how it would tie in with a controller. <Ugg... Jim, this is discussed in that FAQ. Did you really read it?> Aquadyne recommends that you set the calc reactor drip rates, etc, and then set the controller to open the solenoid on the CO2 bottle until the pH drops to 0.15 below your desired pH level. That would mean setting the pH controller to about 8.05 (desired level is probably around 8.2). <Sounds fine to me.>
Now here are my issues/questions. I know the effluent out of the reactor will be low in pH. What level should that be in a dual reactor using ARM media ? <Each piece of hardware is different, and I'd say it is what it is. Get the reactor running and test - this is the best way to get the right answer.> They recommend 7.5, most other media types are around 6.5-6.8. <Yes, but what would be best for your tank?> I have a dual reactor column both with ARM, effluent of one gets pumped through bottom to top of another similar canister. <Is pretty standard.>
Now that being the case, here is the tricky part. If you set the controller as per mfg spec, that means you dose until you drop your pH to 8.05. That's fine and dandy, but will that ever stop the reactor if you have a high turbulent sump and skimmer? <I would think so - why wouldn't it stop the reactor.> As far as I understand, the CO2 actually lowers pH, but if you work it out (similar to degassing it) of the water, the pH will rise back up again. <What is more accurate is to say - if you stop adding CO2 the acid/base reaction stops, the calcium carbonate [acid] becomes normal tank water and the pH will rise up again. Most modern reef systems don't have problems with excessive CO2... this is also covered in that same FAQ.> And if the effluent is at 7.5 with the ARM reactor, it's close enough that with heavy aeration, is the possibility that the pH may never rise possible? <I think you misunderstand the nature of the effluent from the reactor. It is calcium carbonate, an acid. This is only related to the CO2 in that the CO2 was part of the acid/base reaction. Any CO2 in excess of what is in the calcium carbonate effluent [CO2 would be saturated at this point] and this excess of CO2 would pull down the tank's pH further, and this is what is typically discussed in association with calcium reactors. There are some very simple tests to determine if this is a problem in your system - also covered in that FAQ.> Will this open the possibility to inject too much calcium and raise the alk level to levels that I may not want? <No, when the CO2 supply is shut off, the acid/base reaction stops and the effluent becomes normal tank water.>
Also, with the low point on the controller, presumably the calc reactor doesn't run at all at night, since the pH will probably slowly creep below that level, correct? <This is quite possible, yes.>
I've used a calcium reactor before, just not with this media and controller. . . Thanks
<Well then you know... test 100 times - make one adjustment. Cheers, J -- >
Jim

Calcium Reactor
Ignore that last email. <too late.> I saw the powered solenoid on the regulator a few minutes after that. <ok.>
Anyhow, now there are two methods to 'control' the reactor. Some advocate measuring the affluent and controlling the solenoid to output a ph of 6.5-6.7. <I would not recommend this method.> Others have the pH probe in the sump and measure that way, but I'm not sure if you keep it there, whether the reactor will actually work. <Yes it will... if you've read my FAQ, then you know that the 'issue' here is that the low pH of the effluent of the reactor can drag the pH of your tank down, and anything below 8.2 pH isn't really desirable in the main display.> Isn't it possible for the reactor to keep running and raise the alk quite high, but the pH never rises to stop the reactor from running ? <Only if you set it up incorrectly. You should be able to adjust the controller so that it will shut off the CO2 solenoid when the pH in the main system goes too low.>
The main reason is that if you have a nice controller, why in the world would you want the pH reading to be reading 6.5. You would want it to report on the actual pH in the tank in the displays, rather than the effluent ? <I'm not sure I follow...> Thanks, Jim
<Again, if you haven't, please read that URL... I do think it will answer your questions. Cheers, J -- >

Re: Calcium Reactor
<Greetings, Jim, I've also read your other email, but there was some input I wanted to add here... hope you don't mind.>
I just got a calcium reactor. I also have a controller (ph/Octo). Anyhow, wondering what the best way to operate this reactor is. <Well, besides following the basic directions, you should always have calcium, alkalinity, and pH tests available and then run the reactor to match your tank.> It looks like the manufacturer just advises setting it and running it constantly. <For most intents and purposes, this is how it should run. Is how I run mine.> Is this better, or should I hook it into my controller? <This will depend on how the reactor impacts the tank.> However, it looks like the controller bases it on a CO2 valve discharge. <The controller will 'base' it on anything you want, where ever you put the probe.> If I do it that way, I guess I have to get one of those, as you can't just run a reactor pump to turn on when the ph values fall (The CO2 keeps discharging even though the water doesn't, right ?). Any ideas? <Plenty.> Thanks, Jim
<I've got a URL I'd like you read... you will find many answers there:
http://www.wetwebmedia.com/calcreactors.htm
Cheers, J -- >

Calcium Reactor (when to implement)
Bob,
I have purchased a Calcium Reactor for a new reef tank that I'm setup up. Being that I don't have facilities to cure my live rock I will be curing it in the tank for a week or so then doing a 80%+ water change adding live sand and starting the cycling of the tank. When would be the best time for the implementation of the Reactor, should I have it up and running during the curing of the rock, wait until after the rock has cured and the cycling starts, or wait completely until the cycle has completed and livestock is begun to be introduced.
Thanks, Jason
>>
If it were mine... right now. As soon as possible... ahead and during the live rock cure...
Bob Fenner

Not cycling a calcium reactor
Hi bob, i hope you enjoyed your trip...i ordered the Knop calcium reactor which should be here any day, how long till the tanks water conditions are stable, do these reactors need to cycle like regular filters?...will the cycle kill what i have in the tank now?...when i finally buys corals, do they need to be acclimated like fish do?
>>
No cycling involved... more like a chemical feeder... Acclimating some of what the trade calls corals is a good idea... to ascertain whether the specimens are healthy/going to make it... and possibly to isolate unwanted "hitchhikers" that may inadvertently be traveling with them.
Bob Fenner

Calcium Reactor
Mr. Fenner:
Last month you suggest a DIY Calcium Reactor in your answers about my questions involving Calcium Chloride and Carbonate.
In the net, OZ Reef, I found a "Recirculating Calcium Reactor" made by Chris Paris for Reef Aquarium Information Depot. It seems good to me, but I wish to know your opinion about the mentioned device.
Thanks in advance for your help
Flávio Ribeiro
<I am a very big fan of calcium reactors and this design is very workable... definitely the better route to go to assure alkaline reserve, pH stabilization, biomineral availability... Kalkwasser, other additive systems don't even come close in terms of efficacy and safety.
Bob Fenner>

Starting a New Calcium Reactor
Mr. Fenner
I've installed a home made calcium reactor in my system. It has a 2 litres capacity of aragonite, a small Eheim circulation pump (300 l/h), and a plastic needle valve to control the effluent water to the sump. The Co2 is food grade, in a 6 litres appropriated tank, with a pressure regulator and a small needle valve.
<Sounds very nice>
Initially I tuned the CR like this:
- CO2 - 40 bubbles/min.
- Effluent - 40 ml/min.
<Did you measure the effluents pH? The size of bubbles of course is important with the "count", the outflow sounds a bit high...>
Tank initial data, before the CR starts working:
- PH - 8.1 and 8.5 at night
- dKH - 6
- Calcium - 340 mg/l
After 2 days:
In the tank:
- PH - 8.1 and 8.4 at night
- DKH - 8
- Calcium - 360
In the effluent:
- PH - 7.3
<This should, could be a bit lower... less flow and a lower pH... right about 6.5 would be ideal>
- dKH - 30
With this values I add 40cc. Calcium Chloride in order to balance the ratio between calcium and alkalinity.
<One possibility... I wouldn't do the calcium chloride adding as a regular routine though... should be unnecessary with an established routine of melting the aragonite... with which I would experiment as to source/type, size of material... variable in composition, solubility, overall utility>
Also I tuned the reactor for 80 CO2 bubbles in order to achieve the recommended PH value less than 7.0 :
<And/or slow down the rate of flow/effluent...>
In the tank:
- PH - 8.1 and 8.3 at night
- dKH - 15 !!! 
<No worries here>
- Ca - 400
In the effluent:
- PH - 6.8
<Ah, now that's better>
- dKH - 50
- Ca - 600
The corals and the fishes are greater than ever. I don't see signs of stress. ( seven days)
<Yes, well done>
Because the amount of "alkalinity" is so high I reduced the CO2 rate for 20 bubbles and the effluent flow rate for 20 ml/min., and the result is now: PH - 7.4, Ca - 400 and KH - 15 in the effluent. In the tank the PH is 8.2 and 8.5 at night, Calcium - 450 and dKH 13. I am worried about the KH.
<Don't be>
Mr. Fenner, what do you think about this values? The hardness is too high . I would expect some raising but not so suddenly. How could I decrease the high hardiness slowly?
<Allow the system to re-center itself... this hardness is not too high... a great deal of the mineral can/will be "used" by photosynthates... not a worry>
Could you give me some "soft starting approximated values".
<Hmm, you've already stated them yourself here...
Bob Fenner>
Thank you for your attention and precious advice
Flávio Ribeiro
PS : I notice today, that the calcium value inside the reactor was 400 mg/l and in the tank was 450. Is there a reason for that? 
<Likely the soluble portion of your reactant is decreasing... time to switch it out for some new Aragonitic matter... though there are solids in your contact chamber, their solubility is too low for practical use now.>
The amount of bubbling CO2 was intentionally very low ( 10 bubbles) and the effluent about 30 ml/min. Obrigado.
<You're welcome my friend. Life to you. Bob Fenner>

Calcium Reactor
Mr. Fenner:
First thing, I want to thank you for your answer about my new (DIY) calcium reactor.
Secondly, tell you that, with your advice, the reactor is functioning much better:
<Ah, good>
Effluent : ( flow rate - 1.2 litres/hour and 130 CO2 small bubbles/min)
PH - 6.8
dKH - 45
Calcium - 700 mg/l
Tank:
PH - min. 8.2, max. 8.3
dKH - 15
Calcium - 480 mg/l (too high?)
<A tad, but no problem... keep it under 500ppm>
The problem was my ignorance about the KH expected values. I thought that 12 is the maximum level tolerated. I will continue testing the tank and effluent KH and PH just to find the best tuning.
<Yes, a sound plan>
Finally, ask you for a comment about my system. All the animals are great. Sometimes I must deal with some microalgae in excess, mainly over the non-sand bottom and on the rocks that aren't yet covered with coralline algae.
<Very typical, and not really a problem... just a nuisance>
- Volume - 420 Litres (diluted marine natural water). DI from a TWPurifier. Salinity 1024.
- 2 Aqua Medic protein skimmers (airstone) Weekly dark liquid production : about 200 cm3
- About 1/3 of the aquarium volume with live rock
- About ¼ of the bottom with calcareous fine sand (1 cm) The other part is covered with coral gravel (1 cm)
- Mechanical filtration with medium and fine foam.
- Activated Carbon monthly? when I remember.... and only during 24 hours. HW U.V sterilizer
- Sump with 60 litres - Eheim 1060 pump
- Lighting - 5 full spectrum fluorescent. 1 actinic.
15 litres Refugium with little pieces of live rock, calcareous white sand (10 cm) and a growing fast but yet small Caulerpa taxifolia (not for sure). Little organisms are growing there, copepods and tiny red-brown worms. This refugia is "working" about 3 weeks ago. One 15 watts full spectrum fluorescent is on 24 hours. The water - flow is about 18 litres per hour
<Would be nice to have a larger sump...>
- DIY Calcium reactor.
- Livestock:
1 Zebrasoma flavescens, 1 Zebrasoma xanthurus, 1 Zebrasoma veliferum, 1 Mandarin 1 clarkii, 1 Centropyge acanthops, 1 Centropyge loriculus, 1 Gramma loreto, 2 Tridacna crocea, around 40 small Hermit crabs (Calcinus spp. collected here in the island coast) , and 2 big ones (Clibanarius spp.) , 2 Lysmata amboinensis, 1 red local "Atlantic" seastar? (similar to Linckia), 1 Tubipora musica, 1 Catalaphyllia jardinei, 1 Clavularia viridis, 2 Turbinaria sp., 2 Palythoa sp., 1 Sarcophyton sp., 1 Tubastrea faulkneri, Several Actinodiscus.
Mr. Fenner, I admire very much your work. You are doing a great job for this marvelous hobby and for the nature protection. Your web site is full of precious information about what we must not do or buy. Your explanations are clear and simple, an exclusive attribute of people who have good knowledge. I hope that your care lasts for long !
Happy New Year
Flávio Ribeiro
<Thank you for your kind, encouraging words... mean much to me. Bob Fenner>

Re: Depleting Alkalinity & Calcium (a new reactor proponent)
Hi Bob,
<Hello there>
Thank you for your suggestion regarding the consideration to procure a calcium reactor. After intense research via internet, LFS, publications, and others (i.e., Bob Fenner), I brought the Knop calcium reactor Model acan.A  The entire package cost $552 (Knop calcium reactor, media, CO2 regulator, CO2 canister, Pinpoint pH monitor, Rio 800, and shipping). 
<A better purchase, perhaps never better made.>
However, during my research, a couple of sources indicated that the water parameters (pH, calcium, alkalinity) should be ideal reef water quality parameters before initiating the calcium reactor. A Otherwise the system will be continuously off kilter (i.e., extremely high alkalinity but low calcium initially....will continue to have high alkalinity and low calcium post reactor). A Is this true?
<Only to a degree... with a few weeks time/use, the system will center itself with the reactors help>
A What is the best course of action since my system is not balance, as stated in my previous correspondence (alkalinity = 2.8meg/L and calcium = 320ppm)? Should I artificially increase the alkalinity and calcium prior to initiation? A Or perform a significant water change (25%-30%) without adding supplements and allow the calcium reactor to balance and stabilize itself through time? Or a combination of both water change and adding supplements/buffers to reef conditions?
Thank you, Dan
<If it were me, I'd simply rig the new system up and fire it over... You will see. No problems/worries. Bob Fenner>

Calcium Reactor
Hello Bob,
<Hi there>
I am still new to running my calcium reactor, a Knop model C with an UltraLife regulator. 
<A nice combo.>
At this time I only use a PH monitor and I try to keep it running with PH 6.5 and an effluent at 2-3 gals per min. 
<Hmm, this is a bit low... would shoot/select for an effluent pH of about 6.8...>
Although I notice that during the week the regulator constantly jumps up and down @ the PSI which affects the LPM gauge on the left side, causing my effluent PH to jump or drop low leaving air pockets of CO2 in the reactor even though I have a solenoid valve on it. Is this normal for reactors or do I have a bad regulator? 
<Hmm, no... more a "design defect"... that I've mentioned to Daniel (Knop) on more than one occasion...>
Or is this a simple problem that can be fixed by purchasing a PH controller? 
<Hmm, well... possibly... or tweaking flow rate... for now, please just try the not-so-low pH setting... >
Also if I should purchase a controller which do you find to be best to work with, Accu-Max Controllers or PinPoint Controllers. As always thank you very much for your input of knowledge.
<The latter...>
Rob
<You're welcome my friend. Bob Fenner>

Calcium Reactor
Hello there Bob,
I have been reading your section on calcium reactors, and notice you say to keep the effluent PH at 6.8. Although the instructions I received with my Knop calcium reactor state to keep an effluent PH between 6.3-6.5 ideally 6.5. I have a mixed reef of clams soft and hard corals with fish. What should I keep my effluent PH. Also what is the difference in benefits/outcome of keeping it at 6.3-6.5 rather than 6.8? will I still get lots of coralline?
Thanks in advance, Kathy
<A very good question... this preference, suggestion to keep the effluent of these types of recirculated/ing carbon dioxide infusion type reactors is a matter of "safety" as well as expediency... strictly speaking, most folks are well and far better off dealing with a higher effluent pH... enough biomineral and alkalinity make it into their systems for all intents and purposes... and have much less cost (in terms of CO2) and likelihood of problems (algae, pH fluctuations...) at this setting. Do know Daniel Knop of Germany and he is a fine person and engineer... but this is my long-standing opinion/practice. Thank you for asking. Bob Fenner>

Ca Reactor
I finally seem to have the Ca reactor running well. The needle valve that came on the regulator apparently was damaged in shipment and I had a terrible time getting the bubble rate stabilized--it took almost 2 days. 
<The needle valve is the single most important piece of gear on these units... have seen ones made overseas that sell for a couple of hundred dollars US...>
I'm now running about 30-40 bubbles/min. Effluent pH in the reactor is 6.68, and it's about 6.78 at the point where it's dripping in. Ca level in the effluent is 520 ppm and dKH in the effluent is 19 (I checked these last night several hours after I got the CO2 running again--the needle valve had "shut off" by itself yesterday while I was at work so the reactor really wasn't working until last night--so these numbers will probably increase as well). It looks like the Ca level increased about 20 ppm overnight, but it's still around 310. I'm dripping about 90-100 drops of effluent per minute into the system.
<Steady on>
Should I supplement at this point with something that won't effect a downward pH to get the Ca level up, or just wait? (I know patience is a virtue in this hobby.) The system pH this morning was 7.92. 
<Just be patient for a few days here>
Yesterday morning it was 7.96 (but the CO2 wasn't running Wednesday night due to the bad needle valve). Last night the system pH was 8.06 just before lights out. Will these numbers stabilize/increase as Ca and dKH increase over the next few days? 
<Should>
If system pH is less than 8.06 tonight (suggesting a downward pH trend), should I decrease the effluent drip rate?
<No...>
Once this is all taking care of itself, it's going to be great--but still a few days to go, it seems. Thanks for your insights once again.
<Have I recently suggested you seek other input as well? Am fearful that you may be not getting enough points of view... do you participate in the "reef" listservs? You would benefit and in turn help others by doing so... Bob Fenner>

Re: Ca Level
I'm getting a little frustrated with the Ca problem (as I'm sure many are). I finally got the Ca reactor up last night. I checked it today--pH in effluent was 6.65--a little low, I know, but I'm waiting for a new needle valve and can't adjust the bubble rate (about 75/min) below that at the moment. This morning, effluent had Ca of 520 ppm and was 19-20 dKH. I was dripping about 100 drops of effluent/min all day today. I checked Ca level this morning, and it was around 310 or so--it seemed to have increased 20-30 ppm overnight. However, when I got home from work, Ca was at 280! I increased the effluent rate, and added some more of the Tropic-Marin (and tomorrow I need to clean the prefilters again. . .). When I got home a few hours later, the Ca was still at 280. The TM product dosage I used should have raised calc by 20-30 ppm or so, but it hasn't budged. Alk today was at 3 meq/L, down slightly from yesterday's reading of 3.5 as well. I'm thinking now, based on my reading on WWM, that I might need to "jump start" this recovery process with Kalkwasser tomorrow night, as it seems something is "eating up" the calc that's going in there and the levels aren't increasing. My LPS are clearly suffering. Is there any product that I can use to rapidly raise the Ca level without causing major pH or other problems?
<Ah... wish I had the time to read through our corr. here... you are very likely actually the cause of the "diminishing returns" of getting (actually keeping) biomineral and alkalinity in your water/system... Very hard to recall what products you used to use... but your pH is not low... and won't get, stay there if you don't drop too much, too soon the effluent of the calcium reactor into it... and all should stabilize in a couple of weeks... be very careful in placing other sources of biominerals, carbonates, bicarbonates... they are negatively interacting...>
The pH is a little low tonight--it was at 8.02 when I got home from work. After increasing the calc reactor effluent flow and adding the TM Bio-Calcium, it dropped to 7.92 in a matter of hours. Is Kalkwasser for a few nights, in conjunction with the calc reactor, the answer here? 
<No easy, thorough way to answer this here... the overall answer is No... you will likely make alkalinity limiting...>
It should help to raise pH and calc levels, and perhaps burn out whatever is keeping my calc level down, if it's being kept down by some chemical interaction in the water. 
<It would be more beneficial, safer, and in the long term over-all satisfying to enact some thorough gravel vacuuming using pre-made seawater... to remove a bunch of these reactants from that area...>
I'm at a loss here--the Ca level has been plummeting, and nothing seems to be helping. I may also do a partial water change tomorrow to see if that will help--I have a supply of 3-week old premixed water I can use if necessary.
<Ahh, good! Now we're getting somewhere.>
I will help myself if I just know what is going on here! Thanks for your kind counsel once again.
<Clarity is pleasurable, and you are right on the edge of such self-discovery. Bob Fenner>

For the Record (a new, well-upcoming calcium reactor convert)
Calc reactor is up and running. Current water parameters: Ca 320, Alk 3.5, pH 7.94. Ca reactor is filled with 12 lbs of CaribSea ARM, 10 CO2 bubbles/min. 
<Hmm, only ten...>
Recirculating system. Effluent pH is 7.15 for now--but not sure where it will stabilize over the next few days. I'm dripping about 60 drops/minute into the system. (Based on my recent experience, the livestock has been utilizing about 40 ppm/day of Ca--so hopefully these parameters will be sufficient to meet the daily demand and also build the residual level back up, while allowing pH to stabilize and rise as well. . .)
<Hopefully>
Also for the record--I haven't really had a good amount of coralline algae--still get diatoms and have a fair amount of green microalgae on the live rock. I'll take a "before" picture of the tank tomorrow and an "after" in a month or so and send them to you for comparison to do with as you wish.
<Not surprising... given your stated biomineral and alkalinity levels...>
All for now!
<Be chatting. Bob Fenner>

Calcium Reactor
Hi Bob,
Hope all is well. I have adjusted my Knop C calcium reactor to an effluent PH of 6.8 as you advised, and all good. I have noticed a lot of green hair algae, do you think this is from when my effluent PH was running 6.3-6.5? 
<Perhaps>
Also will the coralline algae still rapidly grow/spread, now running PH at 6.8?
<Sure... as long as there is sufficient biomineral (mainly calcium, but about three times as much magnesium...) and sufficient alkalinity, and steady pH, a paucity of competitors, predators...>
I also have been having a problem every few days with clogging on the drip regulator that Knop supplied for the effluent rate. Not sure if you have seen this, it's basically a orange screw type valve (the tighter it's screwed in the less fluid comes out and vise versa). If you know of any fixes for this or something I could purchase/make that would upgrade this valve or replace it, please share.
<Do know of this design defect... my best advice is to remove it periodically and soak in white vinegar... this dilute, "slow" organic acid (acetic) will digest the alkaline clogging materials safely.>
Many thanks in advance, Rob
<You're welcome. Bob Fenner>

Calcium/Ca Reactor
Hello Mr. Fenner,
How are you? I am extremely glad I found you website, it is extremely helpful/insightful. I hope you can help me with my continuous struggles regarding calcium. Before describing my tribulations with calcium, I want to give you a brief background about my 90gallon reef aquarium.
<Okay>
I purchased a Marine Technical Concepts (MTC) calcium reactor 3 weeks ago to help combat/mend my low calcium level. Prior to MTC installation, my water parameters are as follows: calcium = 320ppm, alkalinity = 2.97meq/L or 8.3dKH, magnesium = 1320ppm, and pH = 8.2.
<Actually, all good values...>
Since the deployment of the MTC reactor, the water/operation parameters are:
system pH = 8.22, effluent pH = 6.95, alkalinity = 5.03meq/L or 14.1dKH, system calcium = 320ppm, effluent calcium = 420ppm, bubbles/minute = 54, output effluent = 25 ml/minute, and magnesium = 1350ppm. I use Carib Sea Florida Crush Coral Geomarine Formula for the reactor (recommended by the manufacturer).
<Yes>
The only significant change in water parameter is dKH. My reason to purchase a Ca reactor was to increase calcium, however, it is a still a struggle and have not been rectify (yet?)! I contacted/asked the owner and designer of MTC regarding the high dKH and low calcium level, and they both informed me that the proper usage of the reactor is to measure effluent output flow and dKH, thus, my water/operation parameters are fine. 
<I do agree with this>
Carbonate hardness is what I should be concern with, and calcium testing is not necessary (they (MTC) do not test calcium)! I questioned their statement; I thought I purchased a Ca reactor and not a KH reactor?!
<I understand both your points of view... and yes, you do "need" and want calcium, perhaps more ppm than what you're recording (320)...>
This leads me to seek a second opinion. I want to hear/see your thoughts/insights/comments about my current situation. Is it true of what the folks at MTC said? Is there an imbalance of biominerals, if so, how could I correct it? 
<A few possibilities... The first and foremost is to try another source of material to meltdown (look at other CaribSea products here... for consistency's sake...) and/or next... lowering the pH of the effluent to about 6.8... via slowing down the flow of water more than increasing CO2 input... and then we'll chat after this... It may well be worthwhile in your circumstances to "goose" the calcium (with calcium chloride, perhaps Kalk, perhaps just CaCO3 powder... )>
Is it possible that the high dKH is precipitating calcium in my water? 
<Yes!>
What could I do to increase calcium? I am concern about the constant low calcium available for my corals, although they appear to be happy/healthy at this time.
<Yes... read what you have written... don't be/come obsessed with mere numbers of measures... the health of your livestock is the grand arbiter of all you do with your system... and 320 is not a low number for calcium in an up and going system as yours...>
Thank you in advance for your time and effort.
Regards, John
<And thank you for your clear, concerned expression. Bob Fenner>

Calcium reactors and Kalkwasser
Bob,
My calcium reactor recently broke and I have ordered a new one. In an effort to keep the dKH/ ca rate up I have been adding Kalkwasser to my 300 gallon reef tank. So far I am adding a gallon and a half a day just to keep the dKH at 10.
<I've got to start selling chemicals in the trade...>
I have however noticed a huge growth spurt in my SPS corals over the last week. Here is the question...
Is there any benefit to turning the calcium reactor off every quarter or so and using a Kalkwasser drip for a week or two. Or can I add Kalkwasser once a week or so while using the ca reactor.
<Both... and add a bit of calcium chloride when doing this switch over addition>
I have asked others and no one can give me an answer. My reef buddy from California has asked you many questions and swears by your advice. So I thought you could give me the straight scoop on Kalkwasser additions while using a reactor at the same time.
<Many folks do this... especially in the "forced" culture business side>
Thanks for your help and for all the interesting/helpful tips.
Sincerely,
Neil
<Be chatting my friend. Bob Fenner>

Calcium Reactor questions
Hello Bob!
Thanks for you WetWebMedia site; the information has been invaluable and I have recommended it to everyone I know who is planning or currently has an aquarium (sorry if it results in too much e-mail!)
<Ah, thank you, no problem>
Anyway, I have just installed a Korallin Kalkreactor on my 100 gallon tank and the media I am using is Super Calc Gold. The reactor has been running for approximately 1 week. The CO2 rate is 25 bubbles/minute, at a drip rate of 60/minute. The effluent properties are pH = 6.6 to 6.8, Ca = 440 ppm, Alkalinity = 13 meq/l. The tank water properties are temperature 80 to 82 F, pH of 8.2, alkalinity = 3.4 meq/l, but the Ca is only at 250 ppm. This is actually an improvement, as before the reactor, I was constantly fighting with additives to get the calcium above 230 ppm.
<No worries... Give this program, gear time>
The tank is approximately 4 months old. The invertebrate animals that I have in the tanks are three hard coral (Mycedium, Euphyllia, and Caulastrea), several soft corals (Sarcophyton, mushrooms, and yellow polyps), assorted snails/hermit crabs/Mithrax crabs, 2 abalones, a brittle star, and one Tridacna derasa clam. All the live rocks are covered with purple coralline algae, as are areas of the aragonite substrate. The back glass of the aquarium is gradually being covered with deep pink and blue coralline algae, the color depending on the depth and what light intensity the area sees. Since installing the reactor, the Euphyllia polyps appear to be opened longer and more full, whereas the Caulastrea appears, as my wife said, plumper and also fuller. All the soft corals are also looking bigger, with the mushrooms spreading out more, the Sarcophyton having small buds appear at its base, and the polyps being longer and staying open and out even when the lights go out. The Tridacna is also exposing more of his mantle. So all the invertebrate life looks very healthy.
<Good>
My question is will the reactor eventually raise the tank calcium level to close what the effluent is reading?
<Yes, though the corallines especially are scavenging biomineral and alkalinity as it's produced...>
Or will the coral and other life calcium usage exceed the amount/rate that the reactor is adding, that I should keep adding supplements to speed up the calcium increase to where the reactor can maintain the desired level? 
<Not likely necessary. I wouldn't at this point>
I currently add Salifert liquid Coral Calcium daily, Kent Tech-M magnesium weekly, and Seachem Reef Builder to the make-up distilled water.
Also, am I focusing to much on the what the chemical testing is telling me and should pay more attention to what the tanks inhabitants are doing?
<The latter, always>
Thanks in advance for any recommendations or suggestions!
Kevin
<Chat with you soon my friend. Bob Fenner>

Calcium reactors
<< Jason C here, giving Bob a day off, so to speak. >>
Bob, Have been reading your page for a while and has helped me some. My questions is how to you control your ph when a calcium reactor is running? I have a ph controller but don't really know what solution would be best for raising ph. I am assuming Kalkwasser but I wanted your feedback. Thank you
- Adam Jackson
<< depending on the brand of pH controller, you may have the ability to turn things on and off, depending on the pH you choose. You would use this feature to slowly meter-in the effluent from the CA Reactor, then at an appropriate pH, turn off the circulation pump so that the effluent stops its flow into the tank. If your pH device is just a monitor, then perhaps it would be safest to run the CA Reactor over night, when the tank pH is naturally low already. As far as Kalkwasser goes, a CA Reactor is a high-tech source of Kalkwasser, so there is no need for you to dose it in addition to the CA Reactor. I hope that is helpful - J-- >>