Kalkwasser
Bob-
<Anthony Calfo in your service>
I never knew how much I didn't know about keeping a marine aquarium until I started reading your forum-thanks for being a source of reliable and objective information! 
<always welcome>
My questions today all have to do with Kalkwasser, and I assure you that I've scoured this board for info before penning this inquiry. I just want to be absolutely clear on how to use it before I do some serious damage to my 46 gallon fish/invertebrate tank. I purchased Kent Marine's Kalk along with their Superbuffer dKH. 
<Kalk to be added at night, buffer during daylight to temper their respective effects on pH>
I would appreciate it if you could walk me through the key steps in using Kalkwasser, specifically addressing the following: 1) How do I know if I need to use Kalk? Based on water tests? Therapeutically?; 
<water tests yes my friend. Test to see your drop in 24 hours (48 whatever) without calcium additions and then experiment slowly to see how much Kalk needs to be added to make it up and keep your levels at a desirable range (over 350ppm... around 400ppm would be nice)
2) How do I pick a concentration level for my stock solution? Kent's directions give a pretty big range per gallon of stock. (my main confusion is not understanding the relationship between the stock concentration and the size of my tank--- in other words, what is the relationship between the concentration of the Kalk solution that I add vs. how much I add to the main tank vs. the size of the main tank);
<the more calcareous livestock that you have, the greater the daily demand for calcium...hence the reason for testing to see your net daily need>
3) Is dripping at night the only way I can add it? Or, can I add it to my freshwater reserve that I use for top offs?; 
<the latter is popular but only recommended if it is used fresh (within hours)... limewater that sits for days forms calcium carbonate from the Kalk which is insoluble and useless. In my Book of Coral Propagation (Reef Gardening for Aquarists) I detail another method of adding a slurry of Kalkwasser (whisked in cool water) in amounts that will raise your pH no more than .1-.2. Many benefits... and much more convenient and effective than supersaturated solutions (night drips). Does require accurate test equipment (a digital pH pen ($30-50) or better is advised). Do research more on this application (FAQs. message board forums)) if you are inclined to attempt this. It is very safe if you apply it strictly and carefully, but as a caustic compound can be just as easily abused causing stress or mortality in the system. As always, simply have the knowledge on your side. 
4) How often should it be added? Nightly? During freshwater top offs? During water changes?; 
<nightly in general>
5) I've read of the importance of using a buffer with Kalk, but is the buffer added to the Kalk stock,
<never>
or to the main tank separately?; 
<yes and during the daytime. Kalk provides calcium and buffer provides corroborate so that calcifying organisms can bond the two elements>
6) any other important caveats you think I should know about?
<more is not better with this useful but caustic substance. Always go slow... Good and Bad things should happen slowly in a well maintained aquarium>
Thank you in advance for your time and clearing up my confusion. Regards,
Walt
<best regards, Anthony Calfo>

Follow up (juggling calcium hydroxide... alkalinity vs. calcium concentration... pH...)
Hi Again, since I sent the email last night I tried Anthony's Kalk slurry. Start DKH 15, Calcium 280, PH 7.96 @ 4:40 PM At 6:00 PM I added 10 teaspoons of Bio- Calcium. At 8:30 PM, PH 7.95 I added 1/16 tsp Kalk to 1 cup water , I waited 5 minutes then measured PH=8.02, added 1/8tsp to 1 cup PH 8.03, I continued the 1/8 tsp up to the 6th cup where my PH was at 8.07. This morning at 8:30 AM lights off I measured PH 7.98 Calcium ~320 great! but DKH 19!!?? Why with Kalk additions is my DKH rising so much? (or is it the Bio-Calcium?). 
<exactly, my friend. Kalkwasser only provides free calcium and does not directly contribute to alkalinity. However, the caustic nature of calcium hydroxide (high pH of Kalk) indirectly supports the buffering reserve/pool of a system. Thus, use of Kalk tempers the need for as much Alk supplements and such supplements may be observed to "work" better when used. So... you need to ease up (not stop per se) on the buffer until you fine a good balance (perhaps Kalk daily and buffer 2-3 times weekly all depending on the rate of calcification in your system>
Now I'm afraid to add anything as I know DKH is this range is bad news. Any ideas would be really appreciated. 
<perhaps one good sized water change (unbuffered) of say 20-30% to bring the dKH down a little and then Kalk only for the next several days to raise Ca without impacting alk much (Kalk cannot raise Alk, only support what is there...dissolving Arag sand, calc reactor, etc). After a couple of days resume testing dKH and supplement as/if necessary>
Larry
<best regards, Anthony>

Kalkwasser still....
Hello again Anthony (It's only me from over the sea....)
<Cheers, dear!>
I don't know if you remember, probably not now but approx. 3 weeks ago I was asking about dosing my reef tank with Kalkwasser. I was worried about what I thought was high pH (8.5). Do I take it that 8.5 is actually not high? 
<correct. It is indeed on the higher end... but a reef tank that was say 8.5 at peak day and dropped to 8.3 at night sounds nearly perfect to me>
I say this because you said that a pH of 8.6 would precipitate my high phosphates, support Alk and add free calcium. I thought pH should be around 8.3?
<8.3 is a convenient average and one that is promoted (driven) by industry production of overpriced sea buffers that are mostly baking soda which can only bring a system to 8.3 and no higher easily <wink>. NSW averages on actual reefs (not the whole ocean average which is lower) is around 8.45>
I still have not started dosing as I am still worried about the affects . This is because I now test for calcium as well as Alkalinity.
My tank is 100 gals (Imperial not US gals). The parameters I test for are:
Temp normally 78 has crept up to 82 in last couple of days because of abnormally hot
weather (for England that is!)
<a four degree jump is a rather stressful... do keep a close eye>
SG = 1.024
pH = 8.5 (8.3 at 2.00a.m. yawn!....) liquid drop and tablet tests agree here Ammonia = 0 ,Nitrite = 0, Nitrate between 10 and 20ppm Dry-Tabs Master test kit.
Alkalinity = 250ppm (is this high?) Aquarium System Fastest
Calcium = 500ppm + used all measured dose without sample water turning blue.. previous reading
3days ago 410ppm 10% water change done since then. Salifert CaPro:-Test
<holy cow! The calcium reading is very hard to believe. If you aren't adding any other calcium supplements then you have EXTREMELY hard tap water or it is a clear inaccuracy of the test equipment. You are dangerously close if true to having carbonates precipitate out (a snowstorm). Please do not add ANY Kalkwasser until this is clarified.>
phosphates = 5.0 (very high even straight from tap, main reason for wanting Kalkwasser,
<WOW, yes... 5.0ppm is staggering. Terrible nuisance algae in the tank too?>
hair algae plague)) 
<ahhh, yes>
Dry tablets
My question is this: Can you have too high a reading for calcium/alkalinity and if so what should be done? 
<yes... both are not meant to be held at the high end of the ideal simultaneously. 8-12 dKH for ALK and 350-425ppm calcium is just fine>
will dosing with Kalkwasser make the calcium /alkalinity readings even worse?
<yes, but in different ways. If you push the Ca higher, you may drive the ALK lower through the crystalline precipitation of carbonates. A bad scene. You may need a RO or DI unit to temper your hard tap water. Starting with purified water, you can reconstitute the mix to a more reasonable Ca and ALK levels>
I use Instant Ocean sea salt but am changing to Reef crystals when that runs out. 
<please don't as long as you use tap water (if the high CA is true). You already have too much calcium>
I tested freshly mixed Instant Ocean and found it had mixed a pH of 8.6 (thought it mixed 8.3 ?) 
<usually yes, but you seem to have higher than normal hard water>
I again used both dry tablet and liquid drop methods and they gave the same reading.
I normally dose the tank, sparingly (less than recommended doses) with Iodine, Strontium and calcium once a week (no calcium for the last 3 weeks) since I realized how high it was but you see it has still gone up since then with no additive just a water change
<ahhh.. no supplements, but the water change= definitely hard water evidenced by the jump in Ca. Do consider a DI unit to purify your water. A Kati Ani two column deionizer will be a fine investment>
Taking all this into account , would you still dose with Kalkwasser ?<nope>
I will just add that I have no room/capability of adding a sump/refugium under the tank much as I would like too, I am saving up for a tank that has all this incorporated in it but this will not be happening just yet! All inhabitants seem happy enough (touch wood!).
Many thanks for all your past /future help , I am slowly learning with your help. I have not found
any site anywhere with such an abundance of information and people willing to help like you do .
Also I have learnt a new word from you , so Kudos to you!
<excellent!:)>
Bye for now - Jenny
<until you make the investment in a water purifier, simply do water changes with Instant Ocean, add no calcium or buffer either so long as they are over 350ppm and 8 dKH respectively. Best regards, Anthony>

Re: Kalkwasser still....
Hi again Anthony What a lightning response!!
<we aim to please! Actually... we are just looking for some good fish and chips when we finally do visit the UK :)>
You have confirmed what I was thinking about not adding Kalkwasser yet/if ever. We do have very hard water here.
<indeed... it all points to that. A blessing for keeping marines and African cichlids, but a nightmare for Amazon and pond fishes>
I am now a bit (no, a lot) worried about this snowstorm thing you say I'm close to. Would it have happened when I did the water change if it was going to? Could it still happen and if so what can I do to either stop it or correct it if it happens. 
<the event is unmistakable... it looks like snowflakes suddenly and massively appearing in your tank: like a snowstorm. I can say that you have nothing to worry about if you keep doing regular water changes (providing fresh minerals for the corals) and always replace evaporation with distilled water (else you will concentrate the solids in the display by using tap water for evap top off)>
will I lose my tank inhabitants? 
<it can be fatal yes and must be allowed to run its course... doing a water change during the snowstorm only feeds the reaction with more carbonates. You will be OK if you don't let your Calcium climb above 500 ppm approx>
I was going to do another water change soon but I dare not now! 
<please do! The water changes are necessary and critical. Your tank draws calcium daily... the water changes help to replace it. You simply must add the distilled or RO water for evaporation make up and you will be fine>
Please clarify my next move apart from getting a RO or DI unit (I know what a reverse osmosis unit does but what is/does a DI unit please?) which would you most recommend me to get .
<DI is a deionizer and quite similar to an RO unit. Much better in my opinion because it produces no waste water. It can also be fully recharged with household chemicals>
Thanks again for such a fast response - I am very grateful. Jenny
<My pleasure. Anthony Calfo>

Kalk dosing
Hello and thanks for all of your helpful hints and suggestions!! I am now bringing my pH up to acceptable levels with the Kalk dosing. Was 7.9 and now am keeping it up to 8.25 regularly. 
<good to hear... do check recent posts on the FAQs also about low pH and well insulated houses (atmospheric influence) and opening a window to raise pH in the aquarium!>
The question I have with the Kalk "slurry" is: Do you mix up the solution and then dump all contents from the glass into the aquarium or do you pour it slowly and stop when the undissolved Kalk starts dripping in? This has been a bit vague in your Q&A forum. 
<no worries... both ways can be done. I elaborate on this application in my Book of Coral Propagation if you are inclined. The gist of it though is that it is not so much a matter of slurry or decanted solution, but rather what is your daily demand for calcium (go three days without any dosing and measure calcium before and after then divide by three to get a daily average). Once we figure out how much calcium is needed daily, we then need to slowly dose calcium to fulfill that demand (confirmed by testing that reveals the calcium level isn't straying downward with your x mg of Kalk daily). You could begin with an eight or a quarter of a teaspoon daily (probably a little low if you have a good bit of live rock and/or coral). The only limiting factor here is that regardless of what your daily demand for calcium is, you should never add more slurry or decant than your pH can sustain without jumping my more than .1-.2 (i.e.- before slurry 8.2, after slurry 8.35). For such measures and experiments with Kalk slurries, accurate pH testing equipment is necessary (digital pen or meter). It is uncommon that your tank will not be able to get all of its daily calcium needed through a single dose without spiking pH. Only tanks with massive coral loads need a second dose or more. Remember to only dose Kalk after the lights are out too>
Also in my 60 gallon acrylic sump I have hard and soft corals, snails, emerald crabs and a Niger Trigger, one sand sifting goby and a lawnmower blenny. Is it safe to add a baby Clown Trigger or would that not be wise? 
<not at all wise: not invert safe, gets too large/aggressive, and will kill most tankmates in time>
I have always wanted a Niger and a Clown Trigger and I have the Niger. 
<the Niger Odonus is a wonderful and passive species. An exception among triggers>
Can I get the Clown too? Thanks as always, Jeff Reed
<best regards, Anthony>