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FAQs on Marine Water Quality involving Algal Nitrate Reduction

Related Articles: Nitrates in Marine Aquariums, NitritesAmmonia, Establishing Cycling, BioFiltrationPhosphate, SilicatesNutrient Control and ExportDeep Sand Beds

Related FAQs: Nitrates 1, Nitrates 2, Nitrates 3, Nitrates 4, Nitrates 5, Nitrates 6, Nitrates 7, Nitrates 8, Nitrates 9, Nitrates 10, Nitrates 11,  & FAQs on: The Actual Science Re: NO3 Compounds, Importance, Measuring, Sources, Means to reduce: NNR (Natural Nitrate Reduction, Anaerobic Bacteria), Other Biota, Physical Filters, Chemical Filters... NitritesAmmonia, Phosphate, Silicates, Biological Filtration, Fluidized Beds, Denitrification/Denitrifiers, Bio-Balls, Wet-Dry Filters, R.O./Distilled/Treated Water Chemical Filtrants Deep Sand Beds

Algal Nitrate Reduction Short List: Micro- and Macro-algae, photosynthetic invertebrates (corals, anemones...),

Question About Phosphate, Nitrate, And Control Via Caulerpa 9/23/10
Hi Crew,
<Hello John>
A bit of background leading up to my present question: I have a 100 gallon capacity mixed reef system (75g display, 40g macroalgae/LR refugium) that has been set up 18 months. Previously, most of the
inhabitants (some over ten years in my care, most over five years) were in a refugiumless 55g. A Turboflotor 1000 skimmer is run 24h/ day, chemical filtration is by PolyFIlter, activated carbon and
aluminum-based phosphate media. Water change of 10g (RODI with Instant Ocean), 4-6 times per month. Historically (the first 12 months after setup, roughly) the system ran about 10ppm nitrate, which I checked rather infrequently. I never kept tabs on the phosphate levels, but rather changed phosphate media according to amount of nuisance algae growth in the display. (Other parameters, for what they are worth: 10-12 dKH, 450-500ppm Ca, 8.0-8.3 pH, 35ppt salinity, temp 78F)
<Magnesium levels? Important for the corals ability to absorb calcium.>
About four months ago I acquired a Hanna 'Checker' phosphate photometer (neat little device),
<Yes, and pricey.>
which I started using to keep phosphate down to around .05ppm; my first test upon getting the
device was, if I recall, about .2ppm. I got the photometer to try to end a long standing (years) relationship with Cyanobacteria, which I ultimately sent packing with ChemiClean.
Nuisance algae quickly diminished (as could be expected from keeping a close digital eye on phosphate levels); so did the growth of Caulerpa (C. racemosa) in the refugium, which had previously been growing explosively. Within the last 6 weeks, I've noticed recession and individual polyp death on one Lobophyllia and one Acanthastrea in the display. I finally figured out I ought to test the nitrate level, and it was >50ppm (Tetra kit, so could be 50-100ppm)! I've started changing 10g water per day to remedy this.
<Mmm, I'm quite sure the Tetra Kit measures NO3-N which is total nitrogen.
NO3 is the level that is important to us. A 50ppm reading with the Tetra Kit would result in a NO3 level of about 11ppm...not too bad. As to your coral health, the use of aluminum based phosphate removers can/could cause problems here. With pH levels of 8 or below, aluminum can be released by the phosphate beads and corals do not take well to this. Best to use an iron based remover such as RowaPhos.>
Here are my questions:
On Caulerpa -- since, I assume, the rise in nitrate is at least somewhat related to the slack in Caulerpa growth, should I allow the phosphate level to rise in order to spur this growth?
<Oh no, and why would you want to spur the growth? The Caulerpa growth will be governed by nutrient levels.....isn't that what we are after, control?>
If so, should I reduce the nitrate through water changes before allowing the phosphate to rise (I ask this since I suspect there may be some optimal N-P ratio for Caulerpa growth -- any idea if there is, and
what this ratio might be)?
<No such thing. I'd test with a kit that measures NO3 such as Salifert's kit or a similar kit, see what you read on that.>
On ChemiClean -- I understand the position of many of the WWM Crew members on such products; I won't be hurt by any reminders of the possible harm that can be done with them. One of those harms, I
understand, is the rise in nitrogenous pollutants due to the death of the Cyanobacteria themselves; another is the rise in nitrates due to the death of denitrifying bacteria. I can't imagine that I killed >40ppm nitrate worth of bacteria (surely there would have been heavy collateral damage from an ammonia spike, yes?),
<Possibly, as ChemiClean is not bacteria selective.>
but I can imagine that the ChemiClean did some harm to the denitrifying microbes in the system. Do you think that the elevated nitrate is due mostly to the death of nitrate-reducers?
<First determine what your NO3 level is.>
If this is the case, am I correct to assume that waiting out their return would be the best policy (that,
and not killing them again, I suppose...)?
<If their numbers were reduced, reproduction is quite fast. Is best to go after the root of the problem rather than a band aid fix.>
For what it is worth, I attempted to take a water sample from under the sand bed (deepest past, about 5 inches deep of ~1-2mm aragonite) with a syringe to test for nitrate -- this sample contained exactly as much nitrate as did a sample from the water column (this could indicate either that the denitrification process is not working, or that I don't know how to get a sample from under a sand bed).
<Is a meaningless test. There have been positive results with nitrate reduction (if you indeed have high NO3 levels) by implementing vodka dosing (do not use Absolute, send that to me, use the cheaper grade) but care must be taken doing this as an over abundance of nitrate reducing bacteria can drastically lower
oxygen levels in a system. Better to read/understand thoroughly before attempting.>
Thank you for taking the time to answer my questions.
<You're welcome. James (Salty Dog)>
Best regards,

MAC extant folk, activities, and Halimeda use in SW systems   9/14/10
Hello. I was really disappointed to read on WWM about the shortcomings of MAC. Be this as it may, are there any other [more] worthy organizations with oversight over the marine aquarium trade?
<Actually, the person/s left who "are the MAC" are indeed capable and honest. Previous administrations were "but a farce">
I ask because I want to make sure that I'm only purchasing livestock caught via sustainable methods, and I would also like to contribute financially.
<I do concur with the direction/stance. There are several outfits with this position as well. Many can be found via Net searching. Two premiere examples bar none are TMC in the UK and Quality Marine in the US.>
Your opinion here would be greatly appreciated. Oh, I do have one technical question: Being that I don't have space in my sump for a refugium, would Halimeda be a good choice to keep in one's display for the purpose of nitrate reuptake?
<This genus can work... but does take a good deal of attention to maintaining/sustaining alkaline earth content (mainly calcium and magnesium) and alkalinity... as when it rapidly metabolises, it can/does take up a good deal of both. Please see WWM re this Chlorophytes use>
<Welcome. Bob Fenner>

algae, contr., SW    2/26/10
<Hi Dean>
I have an ongoing problem I hope you can help me with.
<I'll try>
I have a 125G salt tank with about 100 pounds of live rock and 8-10 fish. I have been battling hair algae for about 3 of the 6 months this tank has been set up.
<Look to your stocking/ feeding>
I bought a Aquaripure nitrate removing filter a couple weeks ago and currently waiting on that to establish.
<This is a denitrator. Be aware that these are difficult to run without an ORP computer>
My filtration is a Marineland Tidepool with the single large BioWheel.
<An integrated sump. Does the wheel trap debris?>
Should I remove it, and if so how?
<With the amount of live rock you have you could probably safely remove this, assuming your fishes are not too large. If they are then that is your problem, not the wheel>.
Is this wheel causing my algae breakout?
<Probably not>
My nitrates read 0 but could be a false reading if algae is consuming it all.
<I have to ask -- if your nitrates are so low why have you added a denitrator? All life needs some NO3 and you will deprive your system of it with this>
I feed sparingly and remove phosphates.
<How are you removing this, and what are your test results for it?>
Should I remove the wheel? I can't remove it slowly like removing a few bio balls at a time but can maybe stop it from spinning then remove later. I have done all the tricks for the hair algae there is but I'm convinced it's this wheel.
<You could try removing it, but I doubt if this is THE answer. Combating algae problems is best done by 'attacking from all fronts'. Have you read here: http://www.wetwebmedia.com/algaeconMar.htm. Maybe try a refugium set up to out-compete the algae>
<Cheers, Simon>

Re: Sump Setup?  12/13/06 Good Day to you Tim. <And to you!> Well I am not Norwegian by birth I Have only been in the country for 5 years. I live in Horten, which is about an hour and a  half south of Oslo. Well the main reason that I want to get a sump up and going is to work at getting rid of nitrates. I have heard a lot about this miracle mud that people use in a sump, (more horror stories than anything else) is there any other filters, reactors, or such like that I should get? or that you can recommend? <The miracle mud works by encouraging the growth of macro algae in the sump. You can grow macro algae in your tank for nitrate export without the use of miracle mud which, as you note, is the subject of much debate. You should also consider the use of a DSB - much info on this on the website - as a means of reducing your nitrates. Lastly, you could consider purchasing a sulphur (or other type of) denitrator to reduce your nitrate problems. An excellent denitrator is produced by Korallin, though it is by no means cheap. I would suggest you use the tank you previously suggested with a strong 24hr light, have a DSB in this sump and grow macroalgae. This is the most natural and best way of eliminating nitrate problems and, depending on the what is in your main tank, may also act as a beneficial refugium where you can grow food for tangs or copepods for fish such as the mandarin dragonet. Any further questions, please do not hesitate to contact me. Hilsen, Tim> Tusen Hjertlig takk for hjelpen Tim Clinton

High Nitrate Follow Up Hi guys, <Hello! Ryan Bowen with you> I mailed you a while back about 40+ppm nitrate in my 72g reef.  Here's an update and a few more questions. <Great> * You cited overfeeding (yellow tang and percula).  I've cut back to 2" square of algae and 1/4 square of frozen brine shrimp every 3-4 days.  I can keep 20-40ppm nitrate (Aquarium Pharm kit-hard to differentiate colors at levels this high), but it seems like I'm starving them! (although they both look healthy, tang is just a little pale). <This is a healthy amount!  You may want to offer live macro algae as a supplement for the Tang's color.  (Tang Heaven from http:// www.ipsf.com works well.  20ppm nitrate is still pretty high for a reef, so keep working at it.) * I also went from 15W NO to 65W PC half-and-half 24/7 over the refugium.  A Caulerpa strand I bought (stem with long narrow "leaves" extending perpendicularly) grows under this light, but only so much, then the leaves basically disintegrate.  I've read algae can go into shock easily and I have some Cyano growing in the fuge and on the Caulerpa.  Is this the cause the die back? <Likely.  Time, nutrient control will help.  You may want to look for other types of macroalgae as well- many dislike Caulerpa.  See FAQs for reference.> * Lastly, I added a 5" DSB (170lbs Southdown + 30lbs Gulf View LS) 6 weeks ago.  Reading that you needed some sifting to avoid H2S, I put a 3" sifting star in after 2 weeks, but now I'm wondering if he's depleted the LS. <Highly possible> I haven't noticed the DSB "attacking" the nitrate, or too many bubbles coming up from it. <It's early> Is the star too much for a 72? <Yes, certainly at this age> Should I pull him and add nothing, a cucumber, more hermits (have about 10 now)? OR, has it not been long enough? <Pull him, reconsider in 6 months.> Oh yeah, I also ID'd the turkey wing bivalve from your site.  Several came on my last LR shipment.  Thanks again for all of your help by mail and online content, Jason. <Cool hitchhiker!  Have a great new year! Ryan>

Plants for nitrate reduction Hello to whomever may be answering questions tonight! I just have a couple of simple questions. I'm trying to reduce nitrates. I've been reading the faq's on your site, and noticed that plants have the ability to lower nitrate levels. Could you please recommend a few?  <Mmm, Halimeda, Caulerpa species grow best/fastest for the purpose in hobbyist systems> Would these plants take over my tank or make burrowing difficult for my sting-ray?  <Yes> If so, I'll just put them in the sump, but I was thinking that the tangs might like to graze upon whatever plants were introduced to their home. Thanks for your help, you guys rule (: Ro <These are actually not plants, but algae/thallophytes... you can look up true/vascular plants, use them... or both in a sump/refugium... a good step for many purposes. Bob Fenner>

Re: New Problem << Your nitrates are what? About 80ppm? And you have to add something to adjust pH? It sounds like your water chemistry is directly related to the Tangs stress... I would review your set-up and maintenance, and work out a plan where the nitrates are reduced to ten or less ppm, and your pH stays stable without having to add buffer...> >> Bob,  I guess my next question would be How??  I change 10-15 gallon every other week - I clean the Tide Pool, Pumps, hoses, I vacuum the bottom of the tank. I clean the skimmer cup twice a week, I did not in the past clean the rest of the skimmer because the aquarium shop here said not to, I have now done that.  I use RO water when making new saltwater, I have a powerhead running in the reserve water and a heater.  I don't think I overfeed the fish, I feed one cube of bloodworms, 1/2 cube of Formula One, 1/2 cube of Pygmy Angel food, a small piece of seaweed for the tangs. I have 75 gallon tank with 3 green Chromis, 1 baby Blue Tang, 1 Yellow Tang, 1 Coral Beauty, 1 Flame Angel, 2 sleeper gobies, 3 shrimps, 1 clam and 2 anemones. I also have at least 60 pounds of rock and 60 pounds of sand.  I have noticed that the reserve water has very low PH so prior to doing a water change I always add buffer so as to not shock the fish. Could this be caused by the salt mix?  <To a large extent yes> I use Coralife Salt, if there is something better that you would recommend let me know because I have to order salt.  <Yes, this is actually a poor product... inconsistent, often with varying amounts of alkalinity, calcium... I'd switch to Instant Ocean...> Other than the anaerobic media which is on order, what else would you suggest? <Many possibilities: macro-algae, a Caulerpa algae filter, mud-filter, reverse daylight photoperiod system in a sump... Many ideas covered in various articles here: Home Page > One note to mention, most of the fish in tank is less than 4 inches, only the Yellow tang is larger. You didn't say whether I should leave the algae on the back of the tank or remove it - it does appear to be green algae and the fish do graze on it. <I definitely would leave it!> Thanks, again, Annette >> <You're welcome. Bob Fenner>

Fish and invert tank Dear Bob: I have a 90-gal. salt water tank with a 110 BioWheel hanging off back and an undergravel filter covered with crushed coral. The water falls through 3 holes in the bottom and is pumped back in by a little giant. The lighting is a 47" JBJ Formosa power compact. There's also an oldish skimmer and a power head for circulation. Livestock: 2 clown fish, 1 med yellow tang, 1 med Sailfin tang, 1 small blue tang, 1 large Naso tang, 1 blenny and 1 shrimp; 5 pieces of live rock, 1 star polyp, 1 devil's hand coral, 1 brain coral and 2 anemones. Here's the problem: Changing 20 gals of water every couple of weeks with RO water, and feeding the fish every other day, I'm still getting nitrate levels between .20 -.40  <Probably 20 to 40 ppm, eh?> I like having fish and invertebrates together, but its extremely high maintenance. And I'm still getting a light covering of algae on the glass unless I clean every day. Do you have any suggestions on ways to keep nitrates downs or make the system a little less maintenance intensive? Thanks.  >> <All sorts... the best approaches involve a multi-prong attack at growing macro-algae in the main tank or attached sump/refugium, to limit nutrient availability, produce chemical antagonists to the undesired algae forms, AND spiffing up skimming (like with a larger, more efficient (like needle-wheel technology) fractionator, AND the periodic use (monthly) of activated carbon to remove dissolved organics that aid the problem algae... Please take the good read of the materials placed here: Home Page on these ideas. There's a bunch, and, thanks for asking. Bob Fenner

Nitrates bob thank you for taking my email! I just brought your book conscientious marine aquarist. <Sure you will enjoy, benefit from it> my problem is I have a 55 gal tank, using a emperor 400 filter using standard filter no extra carbon), a sea clone skimmer18 watt uv ster., and 2 03 power heads, 60 lbs of live rock, 60 lbs of live sand, using reef crystal mix and or water. my tank is about 6 mos. old, water changes 20% weekly. and RO top off. I have 1 naso,1 yellow tang,1 purple tang,1 dragon goby, 2 cardinals, 2 damsels, 35 shrimp, <thirty five? I'll assume either three or five> 2 starfish, 3 emeralds, 20 blue legged hermits and 20 snails, 3 anemones, <What types? Could be trouble...> 1 leather, 2 corals. I feed once a day lifeline for the tangs and formula 2 for the others. I do not use phytoplankton or should I? <I would... and be carefully observing this mix... a lot of life for a fifty five gallon tank...> I use reef complete for my calcium levels. no matter what I do I can not get my nitrates down, there running 80+ and very consistent. no matter if I do more water changes or what , tried a nitrate sorb in my filter with no change, I added another filter which is a Rena to help with the standard carbon sponge and fiber media. with no help! my amm. 0:, nitrites 0:, ph 8.2:, calcium 400:, phosphates .1:, I'm getting good skimming from my skimmer and clean the canister once a day and the tube once a week change my filter on my emperor every 2 weeks and clean the Rena once a week. I need help!!!!!!!! should I take out the bio wheels in the emperor? <Maybe... but I wouldn't... you need their help, steady, back-up nitrification here... There is much more you can/should do...> I just bought a 29 gal tank I was going to make a sump out of it with no bio balls putting my skimmer down there and use some live sand bed with plants so the water can run across and then return to tank is that good think it will help? <Of a certainty yes... this is a very good plan.> I'm at the last line now this is my goal in life to reduce my nitrates, LOL I'm at my wits end and really don't no what to do next. thank you , Gary Williams Abington, Va. <Do read over the "Nitrates FAQs" posted on our website: www.WetWebMedia.com, as well as "Algal Filtration FAQs" there... You're well on your way... and seem to have a good and growing grasp of what you might do here. Bob Fenner>

What (Fish) next? Thank you in advance for answering my (and many others') questions... <You're welcome> Tank Info: 55 Gallon Fish only, 45lbs live rock, 20 lbs. live sand (1/2 inch), CPR BakPak 2R skimmer, RIO 1400 and 800 pumps for circulation, JBJ Venice JD1 lighting (combo 10,000K and Actinic). Inhabitants: 2" Canthigaster Valentini, 1" Rhinecanthus aculeatus, 1" Premnas biaculeatus, 3" Genicanthus melanospilos and 1.5" Centropyge loricula <Yikes... this system is going to be getting tight, psychologically and physiologically... soon if not now!> I'm kind of in a position where I'm done adding fish (don't want to overcrowd, unless you think I can squeeze in a small Niger Trigger or Blue Throat Trigger) and want to "enhance" the tank. <No more fish life... you already will have too much> I was thinking along the lines of constructing a basic sump for added water volume and increased water quality. My current setup is running perfectly, with the nitrates levels rising to 10-15 ppm as it nears time for a water change. I would like to add "something" to automate the reduction of nitrates in my system. <Hmm, this sounds good> Will the addition of macro algae (which do you prefer) lower my nitrates? <Decidedly yes> If so, where should this macro algae go? Into a sump/refugium? <And in your main system... yes, where your livestock will eat a good part of it> I don't really mind the CPR BakPak hanging off the main tank, so a sump for the purposes of removing my protein skimmer/heater to an unseen sump is not too important for me. I was thinking I could leave the CPR where it is on the main tank, add a CPR overflow to my main tank, send water down to my refugium where the macro algae will be housed, then send up the "nitrate-free" <let's settle on 'nitrate-lessened'> water via a RIO 800 back to the main system. What type of lighting is required? Will this really lower my nitrate? <A small compact fluorescent is best... Home Depot, Lowe's or pet fish sourced... and yes> What other "stuff" do I need in my refugium? Live sand? Live rock? Mud? <Rock is best... and not to clean out too much, too often> Thanks again. Since I'm mostly done setting up and stocking the tank, I'm looking for new projects to keep my busy... I love this hobby. <Me too. Be chatting. Bob Fenner, www.WetWebMedia.com> - Eugene M. Lee

Success (reducing nitrates) Bob, after continual trate problems in my reef (with a plenum 60ppm, and a Turboflotor skimmer), I added a refugium several weeks ago. I am very pleased that the trates have dropped to 30ppm w/out water changes. Can I expect this to lower into invertebrate safe ranges?  <Yes> Also, I have a 160 with way too high trates, and would like to add a refugium, however, the tank is coppered (I am trying to bring it down now). Is Caulerpa copper tolerant at all? <To an extent will take the copper out of the water... more yes than maybe> I am doing a 40 gal water change, Chemi pure, and a product by SeaChem that absorbs copper. I would really like to get these trates into the 20 (FOWLR). Once again, thanks a million, I have some very happy corals because of your book and web site!! tom <My friend, your successes thrill me. Bob Fenner>


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