Canister Filter

I have a 72 gallon tank with a 500uv Aquatop canister filer and a Tunze protein skimmer. The problem I have is the nitrates. There not sky high, i range from 20-40. I have an anemone and it seems to be affected by it. Fish are fine, but I don't want my nitrates that high. I have read a lot on canister filter in the last few days and they seem to be where the problem lies. Would it be a good idea to remove some of the filter pad and put more chemical and mechanical media in the trays? I also feel the protein skimmer isn't powerful enough. I'm kinda new to this hobby and love it. Need some advice please. Just want the best for the fish.