Hey ya all I'm a new member of Marine Aquariums S.A....n so... Well I would like to start of by asking a question or two. First of all here is my tanks setup. Its a 4 foot tank with sump,live sand and bio balls in the sump.Well I added the sand in about a week ago.I also have a canister filter hooked up, some live rock in my tank.There is a Atman skimmer in my sump too. The problem that I have is with my NO3 level....I just can't get it down!I am performing a 20% water change every month with R.O water too. Should I buy a de-nitrater?