Help with nitrates

[Danielbdn]

My nitrates constantly run high no matter what I do. Today I changed out 20 gal. of a 56 gal. tank and then re tested my nitrates and I get the same reading as before about 40ppm. The tank has been setup for 7 months and I have over a pound of live rock per gallon with a HOB filter and a protein skimmer (no sump yet) I also do 10 gal. water changes weekly.

 

[Dimdim]

Cut back on feeding, i feed twice a day to a ten gallon containing 2 damsels and a peppermint, tested lastnight 80 ppm! Did a waterchange and dosed with prime. Going to cut back to once every two days till it comes back in check