I have 2 reef tanks: one 35L all in one and a 90L both between 1-1.5 years old. For the past year or so my nitrates have been at 0ppm. Recently, my corals have been seeming a little less happy as normal and slower growth. For this reason, I bought reef zlements nitro plus to supplement my aquariums with some nitrates.
I have done around 4 doses (which is meant to raise it by 1-2ppm each time). Every time I dose, I retest after 24 hours, and it is always still 0ppm (even after dosing a little over the max recommended dose).
The 90L has a refugium which may contribute to this, however I have no idea why the 35L never raises. A short while ago, I switched to fortnightly water changes (from weekly) which I was hoping would help but had no effect.
Does anyone have any suggestions or any possible reasons why this might be?
I have done around 4 doses (which is meant to raise it by 1-2ppm each time). Every time I dose, I retest after 24 hours, and it is always still 0ppm (even after dosing a little over the max recommended dose).
The 90L has a refugium which may contribute to this, however I have no idea why the 35L never raises. A short while ago, I switched to fortnightly water changes (from weekly) which I was hoping would help but had no effect.
Does anyone have any suggestions or any possible reasons why this might be?