all good except Nitrate, how do I fix?

[hegeh]

While the real chemists can chime in and correct me, I wonder if the tank is phosphate limited and not allowing nitrates to come down naturally. My recent research shows shooting for a ratio of 10ppm N to .10ppm P seems to keep everything happy and in check. Assuming the Phosphate reading is correct (.04 falls within the acceptable error range for some readers) the tank could actually be at 0 phosphates. I am learning the hard way that a consistent reading of 0 phosphates isn't a good thing. At least not for me and my system (and a lot of others too.)

Yes. Its redfield ratio of N. I learned the hardway too. I was using rowaphos too much that my po4 is 0 and wondering why my no3 is above 100 even i have carbon dose. The i came across this redfield ratio and changed eveything. So i did 60% wc and no3 is 2ppm with phos 0.03. No phos remover till today with almost 1 cube mysis everyday.

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[bertoni]

The Redfield ratio doesn't quite apply here, but for bacterial growth (or any form of growth) to consume nitrate by incorporating it, the organism will consume some phosphorus, likely from phosphate. On the other hand, denitrification occurs when microbes convert nitrate to oxygen and nitrogen gas, and it will work without net consumption of phosphorus. So live rock can perform denitrification without phosphate.

 

[tmz]

I doubt a phosphate deficiency is occurring in this tank with a 0.04ppm reading even though accuracy may be an issue. When a phosphate deficiency comes up a remover like gfo is usually in play.
Nutrient balance ( carbon/nitrogen/ phosphorus see Liebig's law) is important; the Redfield ratio (116 C to 16 N to 1 P)is an en masse measure of these nutrients in the sea and the ratio for may vary form organism to organism. Also as noted , nitrogen removal can occur via anaerobic bacterial activity which releases N to form N2 gas which bubbles out of the tank which can skew the ratio in a given tank toward lower N.

In theory organic carbon can be lower than desired limiting the growth of heterotrophic bacteria which can't get it from CO2 as photosynthetic organisms can. Growing these bacteria is the reason for dosing organic carbon( vodka ,vinegar et al).As they grow and multiply they take up P and N along with the increased available organic carbon and they and their waste products are exportable via skimming. Sometimes nitrogen deficiencies can occur when carbon dosing ,rarely if ever a PO4 deficiency though. None , in my 8 plus year experience with carbon dosing anyway.

 

[hkgar]

I am dosing 50/50 vodka/vinegar at 35 ml/day to my 165 TWV system. I feed very heavy = particularly Nori and romaine), the equivalent of 7 3g cubes. I also have an ATS. Nitrates have dropped to 1 but PO4 is starting to rise, test at .07 today. Is this occurring because of the ratio?

 

[tmz]

I don't think so if it's truly 1ppm . You could try a bit of sodium nitrate,say 1/3 tsp for your 200 gallons to see if it helps bring the PO4 down. O.07ppm PO4 isn't terrible and might adjust on its' own

 

[hkgar]

The .07 is with the Hanna Phosphorus test. Just did Salifert and that is .03.

And, I miss typed the NO3 it s/b between 2-5 with the Red Sea Pro kit.7 and 2 with Salifert.

 

[bertoni]

Our phosphate kits are limited in their precision when the numbers get down to where your tank is measuring. I wouldn't worry much about the phosphate numbers. Nitrate at 2-5 ppm probably is low enough for most animals.