Hi All,
I have a 55gal tank, DSB, wet/dry w/bio balls,5 fish and 13 crabs. The nitrite level is 0, ammonia is 0, PH and salinity are fine but I can't seem to get the nitrate below 80. The tank is 1 year old. I do frequent water changes, every 2 weeks (15 gals). Yesterday, I changed out 20 gals...