[denny_C]

Originally Posted by Randy Holmes-Farley

Bear in mind that carbon dosing can use a lot more N than P, even by Redfield sorts of ratios, because of nitrate potentially being converted into N2 in low O2 areas like sand beds or in live rock. That process is driven by metabolism of organic matter in low O2 areas, so is potentially greatly enhanced by organic carbon dosing..

By that means, one can essentially eliminate nitrate will still having substantial P, and that, IMO, is why many folks find it desirable to use other methods at the same time, like GFO or growing macroalgae.

Alternatively, some folks find it desirable to dose nitrate under the scenario, along for more bacterial growth than the carbon dosing alone promotes, and that allows P to also be consumed.

if i were you i would post this to RC as RHF is posting alot these days and he would help you better in the answers