relationship between nitrate and phosphate?

[miggs76]

My phosphate was up to about .09 (Hanna ULR Phosphorous) and Nitrates were undetectable (Salifert). After a week or so of heavier feeding my nitrates are starting to be detectable (very pale pink) on the salifert test and the phosphate is down to about .05. I've repeated the testing so I doubt it is user error. I read somewhere that there is a relationship between the two. Is it possible to increase nitrates a bit in order to lower phosphates?

[bertoni]

Different organisms consume nitrogen and phosphorus at different ratios. Different food items will vary in the same way. It's possible that your added feeding added more nitrate than phosphate, and allowed some organism to consume enough to reduce the phosphate level. That's hard to know for sure. Given the state of hobbyist phosphate equipment, your results might be within the error range for the test kit, though.

Some people have dosed sodium nitrate in order to reduce the phosphate level in a tank. That can work, so the principle is fine.

[Timfish]

Feeding by corals is a really fascinating and complex subject. Here's a couple of research papers:

High phosphate uptake requirements of the scleractinian coral Stylophora pistillata
http://jeb.biologists.org/content/214/16/2749.full

Coral Uptake of Inorganic Phosphorus and Nitrogen Negatively Affected by Simultaneous Changes in Temperature and pH
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0025024

[Vinny Kreyling]

The relation ship is roughly 16 -1 for removal.
Phosphates will be reduced by 1 part for every 16 parts of nitrate.
That's why people dosing vodka can have problems getting phosphates low.

[tmz]

The answer is yes ;there is a relationship between N(nitrogen) and P( phosphorous); not uniquely NO3 and PO4; but it extends to those .

All organisms including the bacteria that process waste nutients need carbon, nitrogen and phosphorus. The general en masse ratio for marine oganisms is 116C to 16N to 1P(the redfield ratio); the actual ratios for specific organisms vary from that ratio.
The bacteria breaking down wastes will be limited by a lack of any of those nutrients.So, if nitrogen is missing they wont grow as much and wont take up as much phosphate or if any of the 3 is missing growth will stop and the remaining 2 will not be used.
Another wrinkle is that nitrogen is removed in larger proportions than phosphate one would expect from the ratio in the food because nitrogen is not only taken up by organisms in proportions similar to the ratio ; it is also expelled from the tank via anaerobic activity as nitrogen gas.

I feed extra food every other day as a routine ,the extras include nori, flakes , spirulina and krill. The every day routine includes: brine mysis, bloodworm and cylcopeeze.
NO3 is almost undetectable . On the morning after the extra feeding days the PO4 is almost always .02ppm( ie, .01 to .03) lower than otherwise( .03 to .05). I also dose small amounts of sodium nitrate once a week to keep nitrate at or slightly above .2ppm . The PO4 drop is more evident with the extra feeding than the sodium nitrate addition ; perhaps ,the extra ammonia and/or nitrite from the extra food play a role and not just the nitrate or maybe the extra feeding just adds more nitrate than the dosed amount or other elements in the extra foods pick up the pace of nutrient use. Your observations after extra feeding are intdrstingly similar to mine, though.

[Bilk]

My phosphate was up to about .09 (Hanna ULR Phosphorous) and Nitrates were undetectable (Salifert). After a week or so of heavier feeding my nitrates are starting to be detectable (very pale pink) on the salifert test and the phosphate is down to about .05. I've repeated the testing so I doubt it is user error. I read somewhere that there is a relationship between the two. Is it possible to increase nitrates a bit in order to lower phosphates?
I know I'll probably get toasted here, but my situation is similar to yours. I also have a relatively low bio load - 9 smallish fish in a 200. So after reading a few threads about dosing nitrate, that's exactly what I've been doing along with heavily feeding the fish and corals. PO4 is now down to almost undetectable levels and nuisance algae, including bryopsis and valonia, are fading away. <hope I spelled those correctly :uhoh3: Ok I'm ready for my spanking :lolspin:

[bertoni]

We don't know the removal ratio for nitrate and phosphate. I'm not sure where the 16:1 ratio originated, but that is the Redfield Ratio, and if that's the origin, it doesn't necessarily apply here.

[miggs76]

The answer is yes ;there is a relationship between N(nitrogen) and P( phosphorous); not uniquely NO3 and PO4; but it extends to those .

All organisms including the bacteria that process waste nutients need carbon, nitrogen and phosphorus. The general en masse ratio for marine oganisms is 116C to 16N to 1P(the redfield ratio); the actual ratios for specific organisms vary from that ratio.
The bacteria breaking down wastes will be limited by a lack of any of those nutrients.So, if nitrogen is missing they wont grow as much and wont take up as much phosphate or if any of the 3 is missing growth will stop and the remaining 2 will not be used.
Another wrinkle is that nitrogen is removed in larger proportions than phosphate one would expect from the ratio in the food because nitrogen is not only taken up by organisms in proportions similar to the ratio ; it is also expelled from the tank via anaerobic activity as nitrogen gas.

I feed extra food every other day as a routine ,the extras include nori, flakes , spirulina and krill. The every day routine includes: brine mysis, bloodworm and cylcopeeze.
NO3 is almost undetectable . On the morning after the extra feeding days the PO4 is almost always .02ppm( ie, .01 to .03) lower than otherwise( .03 to .05). I also dose small amounts of sodium nitrate once a week to keep nitrate at or slightly above .2ppm . The PO4 drop is more evident with the extra feeding than the sodium nitrate addition ; perhaps ,the extra ammonia and/or nitrite from the extra food play a role and not just the nitrate or maybe the extra feeding just adds more nitrate than the dosed amount or other elements in the extra foods pick up the pace of nutrient use. Your observations after extra feeding are intdrstingly similar to mine, though.

Tom,
Where do you get the sodium nitrate to dose from? I'm thinking about doing this too as I have seen other tanks (that look incredible) on RC dose a little SN from time to time. I just don't want to buy the wrong thing and poison my tank. Thanks

[tmz]

This thread includes a description of the tech grade sodium nitrate I use and a link to the source.
I use only very small amounts and have had no trouble:

http://www.reefcentral.com/forums/showthread.php?t=2349140&highlight=sodium+nitrate