I asked because I've only had an issue with nitrites when I was cycling, but you meant to put nitrates so nevermind. Do you have suspicions on what is causing the nitrate issue? Is there decomposing food that isn't being ate? Is your rock leaching? I've heard florida and lace rock leach but I can't confirm, ghost swears that they don't but the i-net is filled with guys who say they leach.