Dosing Nitrate to reduce Phosphate

[mhucasey]

The problem with the precipitation hypothesis is that precipitation requires high amounts of Ca in a high pH solution(such as limewater). The pH of Calcium nitrate is between 4-7.5(from a google search, i didn't test it). The amount of calcium nitrate added in that first dose would only have added 1ppm Calcium anyhow.

What I have noticed is fairly mild bacterial blooms a few hours after heavy feedings. When I say bloom, I'm talking about mild cloudiness of the water and an uptick in the skimmer effluent. Usually the water becomes very crystal clear immediately afterward. That's essentially what I saw after the first nitrate dose. I have added additional doses since then, without seeing the same kind of bloom.

I attribute the first bloom to very readily available nitrate and phosphate in the water column. My goal is to maintain a slight excess of nitrate so as to not allow the tank to become nitrate limited. I have been fine tuning my carbon dosing and I am pretty sure that i have somewhat of an excess of carbon in the system(using vinegar), also to ensure that carbon limitation isn't an issue.

Anecdotally, the corals seemed to gain deeper color, especially in the shaded areas(Maybe its my imagination). The Clams definitely darkened and expanded more since dosing began. The cyano on the sand comes and goes, a little less each day. As phosphate leaches from the sand from detritus that is already present, water-borne carbon and nitrate are right there to encourage other bacteria to out compete the cyano. The refugia rocks became very clean and the sand in the fuge is better each day as well. I am looking at getting some Strombus snails or small cucumber to clean the sand of detritus. The rock is pretty much clean of any nuisance algae(I've never had hair algae at all).

The corals look great and are growing well. I chucked the Phosphate remover after the first day and still have zero phosphate, with slightly measurable Nitrate. I'd love to see if the effect was repeatable in another system.

 

[Flynnstone]

i too tried dosing nitrates to reduce Phosphates. in the form of Potassium Nitrate (AKA- Salt Peter ) i started slow, then i was adding 2 Tablespoons a day at the end in my 180g. i would get a reduction for several hours, but it always rose back to the initial test results ( Hanna Tester) perhaps it was leaching out of my rock, but this took place for weeks without change.
Lanthanum Chloride works, but my experience with that product only offered short term results.

 

[reefmutt]

I'm amazed that nobody else is trying calcium nitrate in their systems..
Nobody else reading this, I guess..
I'd love to hear some other experiences with it.

Sometimes po4 can leach out for a long time..

 

[mhucasey]

I think many people are using this method and just don't know it.

To explain: there have been a few enterprising reefers who have tested the zeovit additives like zeofood and found that they had nitrate. It makes sense why they would contain nitrate though, if the concept of the nutrient ratios holds true. Dose some carbon with a bit of nitrogen and the only bacterial growth limiter is phosphate. So its possible that Zeovit users have been practicing this all along.

I have some of the zeovit LPS amino acids and they triggered a significant result with a nitrate test. Interestingly, the Amino Acid HC for SPS showed none.

 

[Big E]

I'd suggest that if you do see any "darker" colors it's from the corals intaking the nitrate, not the lowering of the phosphates. I've run high phosphate levels & the corals are darker not lighter..........less PO4 = lighter corals.

As a general question, why do you want to chase the number down to zero? I'd only concern myself with that if you have some pest algae that is affecting the acros. There are a lot of reefers with knockout colors with PO4 of .03-.08 & & trace nitrate readings.

Zero phosphate can be dangerous especially at higher nitrates..........be careful with that dosing.
http://www.advancedaquarist.com/blo...nitrogen-increase-coral-bleaching-probability

From the article------
"Researchers from the University of Southampton based at the Coral Reef Laboratory in the National Oceanography Centre, Southampton, found that an increased supply of dissolved nitrogen compounds in combination with a restricted availability of phosphate results in phosphate starvation of the algae. This condition is associated with a reduction in photosynthetic efficiency and increases the susceptibility of corals to temperature and light-induced bleaching."


If your goal was to get better colors I would suggest that your PO4 levels were fine & you just needed to add a nitrogen source. Aminos might work(nitrogen source) and get you to the same goal without putting your acros in danger.

Just my opinion, but I wouldn't run 0 phosphates with that high of nitrate readings long term........seems like an accident waiting to happen.

 

[RickMartin]

The problem with that article is that it doesn't specify what they consider high levels of nitrates, so its basically useless. I don't remember anyone here raising their nitrate levels above trace readings, which depending on the test kit is probably under 5.

 

[RickMartin]

Do you have any references for the above and how high is too high? IIRC the last paper I read about it showed that levels of .5 really only resulted in less dense skeletons, but didn't otherwise impact overall health or growth.

Effects of elevated nitrogen and phosphorus on coral reef growth
Kinsey, Davies 1979

Abstract-Long term phosphate (2 μM) and
nitrogen (20 μM urea + ammonium) enrichment
of a patch reef at One Tree Island, Great
Barrier Reef, caused >50% suppression of reef
calcification. This is attributed primarily to the
phosphate.

 

[RickMartin]

For convenience here are the conversions of the above levels
95 * 2 / 1000 = .19 ppm phosphates
62 * 20 / 1000 = 1.24 ppm nitrates

 

[gbru316]

For convenience here are the conversions of the above levels
95 * 2 / 1000 = .19 ppm phosphates
62 * 20 / 1000 = 1.24 ppm nitrates

isn't the prefix micro (designated by u) 10e-6?

10e-3 is milli.

 

[RickMartin]

I used the formula provided in this link
http://www.reefcentral.com/forums/showthread.php?t=2206653

 

[mhucasey]

The colors themselves were deeper and darker, which I also attributed to nitrate. Higher phosphate tends to increase zooaxanthellae algae densities, masking the coral's true colors and usually resulting in brown corals.

My goal is to reduce algal density to see the corals colors so a reduction of Phosphate is a priority. The amount of Nitrate I am maintaining is very low, less than 5ppm and just above 0ppm. High nitrate, say in excess of 20ppm with zero phosphate can have some toxicity(although there are some amazing systems with much higher nitrate values than that).

I feed constantly in my tank, which allows me to keep a high bio-load of healthy fish without aggression. Therefore there is always some excretion of both ammonia and phosphate, meaning trace levels are always present in the water column. Its just not physically possible to have a system with truly "zero" phosphate or nitrogenous waste with a bunch of fish.

 

[mhucasey]

I'd suggest that if you do see any "darker" colors it's from the corals intaking the nitrate, not the lowering of the phosphates. I've run high phosphate levels & the corals are darker not lighter..........less PO4 = lighter corals.

As a general question, why do you want to chase the number down to zero? I'd only concern myself with that if you have some pest algae that is affecting the acros. There are a lot of reefers with knockout colors with PO4 of .03-.08 & & trace nitrate readings.

Zero phosphate can be dangerous especially at higher nitrates..........be careful with that dosing.
http://www.advancedaquarist.com/blo...nitrogen-increase-coral-bleaching-probability

From the article------
"Researchers from the University of Southampton based at the Coral Reef Laboratory in the National Oceanography Centre, Southampton, found that an increased supply of dissolved nitrogen compounds in combination with a restricted availability of phosphate results in phosphate starvation of the algae. This condition is associated with a reduction in photosynthetic efficiency and increases the susceptibility of corals to temperature and light-induced bleaching."


If your goal was to get better colors I would suggest that your PO4 levels were fine & you just needed to add a nitrogen source. Aminos might work(nitrogen source) and get you to the same goal without putting your acros in danger.

Just my opinion, but I wouldn't run 0 phosphates with that high of nitrate readings long term........seems like an accident waiting to happen.

I do dose amino acids, but as a nitrogen source I think they are not a precise measurement. As for the acros, they have never looked better.

I haven't added any new nitrate for 5 days, and don't expect to re-dose until the ratios get out of whack again. I keep precise notes on how much I dose and when, and eventually I hope to add just the right amount of nitrate to my vinegar dosing to maintain the excess of nitrate, but I need more data before doing that.

 

[gbru316]

I used the formula provided in this link
http://www.reefcentral.com/forums/showthread.php?t=2206653

i think that formula is incorrect. I sent a PM to the poster of the formula to verify. I haven't had chem in a few semesters, but I do vaguely remember molar concentration converstions, and I use scientific notation and metric prefixes every day in my industry.

 

[RickMartin]

i think that formula is incorrect. I sent a PM to the poster of the formula to verify. I haven't had chem in a few semesters, but I do vaguely remember molar concentration converstions, and I use scientific notation and metric prefixes every day in my industry.

Well I haven't had chemistry in like 40 years and never use it other than the hobby, but perhaps it has to do with the answer being in ppm

 

[gbru316]

Well I haven't had chemistry in like 40 years and never use it other than the hobby, but perhaps it has to do with the answer being in ppm

I was wrong, the issue was that the link stated 62 g/mol, but we needed ug/umol. Carry on :spin1:

 

[Big E]

I do dose amino acids, but as a nitrogen source I think they are not a precise measurement. As for the acros, they have never looked better

Yeah, I don't think it would be measurable on a test kit unless you overdose, but you would be able to see it in the colors. I don't use aminos but just suggested that as a nitrogen source.

As far as higher phosphate levels go I think sometimes we need to quantify the actual numbers. I've run as high as 35 to 50ppm & the colors were the same. I've got a ton of pictures at different levels & quite honestly you couldn't tell the difference from .08 to .35

My nitrates were always zero. Of course algae becomes more of a factor at those high levels & calcification to some degree.......... those are more the main reasons why people need to keep them lower. I like them just below .10ppm.

Reef Bum & Rigleautomotive both keep detectable levels in both nitrates/phosphates & you can't argue with their results.

Like you say, there's plenty of ways it will work.........it's just finding a good balance. I try to focus on the corals & not so much the numbers.

People always seem to miss the fact that what readings they get is what's left after the corals, bacteria, algae, ect get their share. That's why a tank at .03 with two fish can have starving/bleached corals & a tank with 30 fish at .03 has colored up healthy corals.

I asked Randy about this back in '07 & bought the nitrate powder but never did anything with it because I wasn't really having any issues at the time. I was more interested in finding a sweet spot or balance than keeping levels at zero.
http://reefcentral.com/forums/showthread.php?t=1032679

Interesing thread...........keep us updated on your results. Some pictures would be nice too.

 

[mhucasey]

I need to get some current shots for comparison, but this is what I came up with - first a shot of the tank and display refugium, then a before and after - focus on the green shaggy acro - i looked for two pics from before and after that showed the same coral with the same lighting. I have two cannon pendants, one white, one blue, with par38 full spectrum accents. When I take pictures I find that turning the blue cannon off results in an iphone pic that is pretty representative of the actual colors.

Anyway focus on how pale the green acro is under the branches. Its to the left in the after pictures and the color is much more saturated, plus its darker underneath the branches.

One of the points of doing this dosing in the first place was to get more color in my corals - get rid of the brown. I think after bringing the nutrients down farther and playing around with the light I hit my limit. From above the corals are very colorful - the fourth pic shows this. The LEDs just produce too much directional light, so i'm switching to T5. The superior spectrum and spread of the t5 bulbs should get me what I am looking for as far as color.

 

[swcc]

ok... dose vinegar andat x dose per day, nitrate is zeroed and leaves P... so, to combat this you add more N? how about lowering the dose of vinegar so not the N is not zeroed? Sure the dose is cheap, but, why add when you can simply reduce. The reduction in turn will lower bacterial levels some, thus carry less weight in O2 utilization and other effects that holding the larger bacterial count will manifest.

 

[RickMartin]

ok... dose vinegar andat x dose per day, nitrate is zeroed and leaves P... so, to combat this you add more N? how about lowering the dose of vinegar so not the N is not zeroed? Sure the dose is cheap, but, why add when you can simply reduce. The reduction in turn will lower bacterial levels some, thus carry less weight in O2 utilization and other effects that holding the larger bacterial count will manifest.

Won't that also increase the P? The whole point is to get lower P levels not higher

 

[mhucasey]

No, maybe I was unclear. The idea is that with excess carbon and nitrogen, as soon as phosphate appears it will be taken up by bacteria(phosphate limited system). I detect trace amounts of nitrate on the test with zero phosphate in my current steady state. Before this I would always show zero nitrate but have some measurable phosphate. So far, maintaining this trace amount has only been with periodic dosing of small amounts of nitrate.

I don't actually know if I have excess carbon, just right, or too much. Based on the guides, I should be just right since I get light algae growth on the glass, none on the rocks, but no white bacterial films. I add additional doses of vinegar or vodka from time to time and don't see any visible reaction(like a major bloom), so I don't think I should go any higher with my dose than the ~50ml of white vinegar I add now.

Normally feeding the tank adds both nitrate and phosphate to the water in close to the proper ratio, and the bacteria break this down, but as most people experience, phosphates build up eventually - thats why most people use GFO to scavenge this bit of phosphate. I just want to maintain the ratio or slightly tilt it toward nitrate rather than phosphate.

I hate to dose anything periodically, because its too easy to forget to do it. I would love to add a trace amount of nitrate to my carbon source which is dosed in automatically. This trace amount would equal the amount I add periodically, just spread out over multiple doses. Im still dialing in the exact amount I need to add to keep the Nitrate slightly positive.