Dosing nitrate or other nitrogen sources to reduce phospahte

tmz

ReefKeeping Mag staff
Premium Member
These a few posts of mine from a thread on the advanced topics forum entitled: "Dosing nitrate to reduce phospahte" ; fyi and discussion:



Interesting thread . Most have done a good job getting past some of the nonsense and irritation and name calling and stayed on point.

A few comments to consider:



It's certainly seems counter intuitive to dose nitrate or another nitrogen source but it may make sense.

The redfeild ratio is rather useless as a guide other than to offer perspective on the general en masse proportions of carbon(C)106:N) 16: 1 P in ocean plankton. Organisms may approximate those levels but some including some bacteria vary significantly . Even if food put in the tank is close to those proportions, the activity in the tank may not use them in those proportions. All in all, trying to use the redfield ratio to obtain a generalized optimal N to P ratio seems convoluted. Using tank levels of N and P vs natural seawater levels seems smarter and more direct.

To clarify the idea as to why dosing N might be necessary, a brief look at the three major nutrients coming in and going out of the bio available mix in the tank may be helpful

Organic carbon coming in for the most part with foods can be used for energy or sunk in refractory( non bio available) organics like humic and fulvic acids ;some may also be contributed by photosynthesis. So, the amount coming into the tank is not really the bio available amount in the tank.
In many tanks it seems there is a shortfall as N and P levels climb. If there was enough organic C, the bacteria would use up the N and P too and tank levels would approximate nsw levels ( PO4 ca .005ppm and NO3ca. 0.2ppm) more often than they do. This imbalance is the basis for organic carbon dosing( vinegar, vodka, pellets, sugar, etc)
Unfortunately, hobby level measurement of organic carbon is not possible. Even high level analyses with $ 50 K analyzers don't really tell you what organics are present and whether they are bio available. So, we use No3 and PO4 as sort of a surrogate measure for nutrients, often ignoring organic carbon.

The proportion of N in and N out varies vis a vie the proportion of P in and P out too. The bacteria , consume C,N and P for food( ie, they assimilate them) and in turn are exported primarily by skimming . Even if we assume they have a perfect 116C to16Nto1 P biomass and the food into the tank also has these exact proportions,more N will be exported than P.
Anaerobic activity where the bacteria use NO3 for oxygen when free oxygen is used up exports extra N . NO3 is reduced to N as the oxygen is taken ;some of the N which binds to other N forming N2 which bubbles out into the atmosphere. How much of this occurs is variable from tank to tank but it does deplete nitrogen in addition to the nitrogen assimilated by the bacteria as biomass;there is no other such exit for P .
This is why many use gfo or other adsorbents and or precipitants for PO4 along with organic carbon dosing.

Sometimes, N levels at 0 may induce some coral paleness, perhaps from an N deficiency for the zooxanthelae or the coral itself. Some think adding extra N via sodium nitrate or calcium nitrate will remedy that and also help the bacteria to reduce more P. Very plausible positions,imo. Some ,including me prefer to add extra N via aspartic acid and amino acid which also adds some organic carbon.



Herringfish,

I'm not sure it matters a whole lot which source of N you use but as requested this is is my thinking:

Potassium nitrate(KNO3) adds potassium I might not need or want. I would use it if I measured and needed more potassium.

Calcium nitrate(CaNO3) adds calcium which I'd rather add in normal doses balanced with carbonate alkalinity.

Sodium nitrate(NaNO3) adds sodium but I don't care about that as much as the calcium or potassium since there is so much sodium in the water(10,500ppm) any small addition won't affect ion ratios very much at all and will level out with water changes . I've tried it.

Aspartic acid contains nitrogen and organic carbon in the form of an essential acidic ammino acid that living things incuding corals use . I account for the carbon part by reducing the vodka dose to off set the extra carbon. I use L aspartic acid from I herb .com,an online health food vendor ,ca $6 for 250 grams.
It only takes 4 grams 2x per week for 650 gallons to get N where I want it 0.5 to 1ppm . I'm still observing it since I started it just 2 weeks ago. Sps coral color seems to have gotten richer and lps seem fuller but I may just be seeing what I want to see.

I've been dosing vodka and vinegar for organic carbon over 5 years with very good results. in keeping NO3 and PO4 low. Sugar even in small amounts caused coral browning and some recession. There is at least one study linking excess glucose to coral mortality. So, I don't use any sugar anymore.

Since it has virtually no water in it and 80 proof vodka is 60% water I discount the vokda by 2.5 ml for each gram of aspartate I dose. I I would discount 5% acetic acid vinegar by 8ml per gram of acetate dosed.I'm sure a more precise comparison of organic carbon content of each is possible but that's close enough for me . I use the same conversions for any solid organic carbon source, eg, sugar, vitamin C, etc.


I don't know that dosing nitrate in any form is necessary as a standard proceedure. If there is food in a tank or breathing fish some nitrogen( ammonia, nitrite or nitrate) is there. Again nsw levels are around 0.2 for nitrate and .005 pmm for PO4 at the surface. I think it's still experimental and I'm just tweaking things a bit for now. I like to get just a tinge of pink viewed from the side of the salifert NO3 test.
 
You are welcome Gary,
Yes, that thread is lengthy . Much of it is cyber jerk stuff,ie, name calling ,obfuscatory pedantry with little information particularly in the first 10 or so pages. I summarized the salient stuff as well as I could on that thread and here because the technique is interesting and I felt much of the early posting was misleading. IMO the subject deserved better than it was getting in advanced topics. I may have missed a useful tid bit; so, those who'd like to read the whole thread may form a different opinion.
 
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Your posts always leave my head spinning Tom :). What you propose makes sense to investigate for sure. Realistically our tanks are tiny microcosms of a natural reef which are surely deficient in some ways from that environment. I've gradually become a big fan of boozing up my tank with vodka dosing. Would love to hear your long-term experience with it as things progress.
 
I'll post it , Mike . It's early to conclude anything meaningful. After 3 samll doses of aspartic acid; now reduced t o4 grams once a week, NO3 is steady at .5 to 1ppm. Coral color looks a little reicher to me. A few more diatoms are evident, not a problem by any means. Som small wisps of algae in a few spots. The extra N has had no discernable effect on PO4 reduction but it's too soon to tell. I'm planing to keep dosing for a couple of months.
 
This is an area where the reef hobby could learn from the planted FW hobby. It's commonplace to dose "bad" nutrients in planted tanks in order to maintain the ratios that support the best plant growth. The corollary in the reefkeeping world is dosing "bad" nutrients to maintain the ratios that support the best bacteria growth (or coral growth, though I'm not sure we're at that level of precision or need yet).

Despite the obvious logic here, it's amazing how vehemently opposed some people can be to the idea that dosing nitrogen could be good for a tank...
 
Nate, I uderstand balancing N and P is a common practice in planted tanks. The trick here is to discern whether it is useful in reef tanks, under what conditions ,at what levels and in what specific forms of organic carbon and nitrogen. Who knows maybe dosing ammonia is next. If you think folks are upset about dosing nitrate fly that one out there.


I think monitoring N levels when dosing organic carbon is useful but often undetectable isn't really zero given the limits of hobby grade test kits.

However, in a fed tank with lots of fish exhaling ammonia I'm not sure it's necessary to dose N in any form but I'm trying it in very small amounts.

I have been surprised by how little sodium nitrate or aspartic acid it takes to generate 1ppm. Only 4 grams for 650 galons 1x per week seems to be enough. So. my advice for anyone else who want's to try it is go very slowly and monitor levels.

Chris in your case with no PO4 reduction from carbon dosing and 0 nitrates , it seems the bacteria are N limited and the organics you are dosing are just building up and fueling some cyano. The bacteria involved need organic carbon, phosphate, nitrogen and oxygen( as oxygen or from NO3). If one is missing the others will go unused an something else will use them, perhaps in an undesirable way. They also metabolize some metals and other minor and traer elements but feeding and water changes usually give us enough of those to go around. I have ,however ,been dosing very small amounts of iodide and iron for the last 5 months just to be sure there is a little around .
 
This is an interesting idea and is totally logical. To dose No3 for same reasons people dose carbon. I have not read that thread, not enough time today. But do have an understanding of the redfield ratio and nutrients in seawater. May have to try it on one of my tanks. A perfect example. This aquarium is carbon dosed for nutrient control. As No3 has always stayed undetectable, po4 can at times go up to .09-.16. The tank does not have many fish and normal feeding isn't enough food. I have deliberately been overfeeding this tank. At times even tossing the food in the filter bag just to create some more nitrification. So why go through nitrogen cycle to create no3 if nitrate could just be added.
Another thought is to add a trickle filter. The old school bioballs in wet/dry. The nitrate factory. This could allow me to begin keeping non photosynthetic coral and have an automatic continues feeding.
 
Thougt about a trickle ifilter. A trickle filter will give you nitrate from ammonia but won't add any nitrogen to the overall N total in the tank without some extra decaying matter. external .
Some corals take up ammonia directly and some bacteria take the N directlly from NH3/4 as well.
So, now
I'm thinking about which type of nitrogen to dose and need to figure out if it mattes whether it's NH3/4, NO2 , NO3, some decaying food source,,fish urine a vitamin ,an ammino acid or something else.
 
Nice summary. I guess I was one of the cyber jerks, not really my intention.

Since it was brought up here, can I ask how bioballs, wet/dry or trickle filters can create only n, not p? I never did understand that. I actually thought they help gas of ammonium and thus lower N.

I would not mind to have detectable no3 in my tank but it's impossible for me w/o dosing nano3.

/sent from phone
 
I don't think , you are a cyber jerk . A lot of the thread just got nasty and confrontational ;some of the attitudes made it long and hard to read.

Trickle filters provide surface area for ammonia oxidizing bacteria and a supply of water that is highly oxygenated from surface gas exchange. As you know, these bacteria oxidize the N in the ammonia to form NO2 (nitrite) and then NO3 (nitrate). There is no P in ammonia but likely is some in the decaying food that produces the ammonia unless the ammonia is dosed directly . So, trickle filters don't generate any N or P; they change the form of the nitrogen in the ammonia, eliminating the ammonia via the nitrification process..

I think like most bacteria, these bactria take up some P for their own needs .
Since they grow on surfaces, they aren't likely exported by skimming for example and any P that they store and use would likely stay in the tank. So, they don't add any and don't really help in reducing any P.
 
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If we end up starting to dose ammonium nitrate, I'm gonna have to put my foil hat on and start fearing the gubment :)
 
However, in a fed tank with lots of fish exhaling ammonia I'm not sure it's necessary to dose N in any form but I'm trying it in very small amounts.
well... let me know how it goes.

You know my particular case involves LOTS of fishload. I don't think N dosing would help my aquarium but I might be wrong.
 
This makes me think of the phyto studies i did. I ran a small 30g tank some years ago for non photosynthetic soft coral. They fed on live phytoplankton. In order to maintain the tank in a constant phyto bloom I dosed plant ferts (N, P, mineral and trace element) sometimes I made water changes using old water from a heavy loaded fish only system with large trickle filter. Worked well. And I was able to test nutrient reduction with phytoplankton population raising.

In a carbon dosed system some bacteria take up No3 nitrate. Its being tested. Not sure if the source matters. Although with extra decay there is a risk involved but may actually lead to a more diverse food chain and ecologically healthy tank.
 
Yes, I agree decay is an issue. However, one study asserts the heterotrophic bacteria encouraged by organic carbon dosing actually take N from ammonia directly,thus reducing NO3 due to less nitrifcation in the first place. So, I wonder if NO3 is useful to them directly; probably is.
 
Well since I completly stopped dosing vodka/vinegar my Nitrates have jumped to .5 and there is algae back on the glass. The corals look great but the cyano is getting worse, I just did a water change and and replaced the GFO on Saturday.
 
I've been dosing sodium nitrate for a few months and I'm seeing positive results. I keep nitrate elevated at 2.5-5 ppm and this seems to keep PO4 at <0.05 ppm all by itself. I may switch over to L aspartic acid for the reasons you stated above. What is your dosing regimen if I may ask? Do you mix it with RO and dose gradually throughout the week using a doser?
 
Good thread..........tagging here and with a few comments---

Have you considered adding foods that have a high content of protien. Essentially more protein = more N.

I'm not sure what those foods are exactly. I know mysis is high in protien and possibly some of the Rotifeast, Oyster feast type foods. I know you're also adding PO4 but the N to P ratio will be different than a lower proten food.

What I'm getting at is more N in foods would add to the zoo producing the correct amount of Aspartic acid as it's known to be bio synthesized already by corals. In turn faster growth and better colors.

What's the goal? Are you trying for better color? Better growth? Or just trying to balance PO4 and nitrates?

I like the idea of adding an AA that you know exactly what you're adding, but those commercial mix recipes of AA's don't seem viable to me. It's like adding your whole cubbard of spices for a recipe when you only need pepper.
 
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