This is a follow up on a previous post on cycling the tank. The tank is fully cycled now and is the happy home for tetras, rams and a couple of gouramis. The question is since the tank has just finished cycling, I need to do a big water change to bring the nitrates down, should I vacuum the gravel when I do the change or just siphon out water since it's pretty new? I understand that the majority of the bacteria are in the filters but some will be in the gravel and I don't want to start a miinI cycle. What say you?