Canister filter will put out a lot of nitrates. There are may way to set up a reef tank but aerobic filtration like wet dry filter, canister filter or fluidized filter are not the correct way to set up a reef tank, especially a anemone tank.
It is possible that I am wrong, but from your question, you seem to be new in salt water/reef keeping, please do not start out with keeping an anemone. You will likely not able to keep them alive. Clown fish will do fine without anemone. Most people would recommend that in order to successfully keep anemone, one must be well past the beginner stage. IMO, anemone and clown fish brought more people to reef keeping than any other reason. It also responsible for most of the anemone's death.
Please think careful and pay attention to my advice above.