Hi, I have a 55 gallon fresh water Cichlid tank 2 aqua clear 110 hob filters. 1 air stone. 1 Texas and a couple Gouriams. I am not able to get the nitrates to come down. The nitrates at are at 80 ppm. I am using the api liquid test kit. The amn-0 nitrite-0 ph-7.5 kh-2 temp 80degres F. I did not always change the water every week like i should have. After reading reading here about what the nitrate is and understanding it I have been trying to lower the level. I have done several water changes this week but the nitrate has not moved that much. I have always used a gravel vac and the gravel is clean. Anyone have an opinion on how I can lower the nitrate level.