high nitrate level from dosing?

Deep Reef

New member
my 120 DT with a 40 gal sump is over 2 years old. I have been battling GHA and seemed to have beaten it. work got really busy and I missed a cycle of GFO change. Some GHA has returned. I have been running GFO and vinegar dosing. I check my parameters every other week. The weeks in between (every other week ) I perform a 20 gallon water change. This last week I noticed high nitrate levels of 20ppm. my other parameters are Salinity of 1.025, Ammonia 0, Nitrite 0, Temp 78 deg. F, Phosphate 0.0, Alk 6.4, PH 8.2, Ca 300, mag 1000. I know mag and Ca are low and I have been dosing Kalk to get them up. I just recently increased the kalk from 1/2 tsp/gal to 1 tsp/gal.

My Nitrates have always been 0. could it be the Kalk or the dosing that is causing this increase? any suggestions?


New member
I have a feeling the gha is masking your phosphates. If you know someone with a Hanna phosphate test kit. Ask them to test your water.

I've never heard of dosing causing nitrate issues.