ok, so I have a 150 gallon tank that is pretty heavily stocked. I have 2 large canisters filtering this tank, the cascade 1200 and cascade 1500. The 1200 has 4 trays for media and the 1500 has 5 trays. What I have been doing is each week cleaning one tray(a different tray each week) in a bowl of tank water, so that I don't kill any beneficial bacteria. Would you say that I have enough beneficial bacteria where I could clean one tray out a week with tap water or should I just continue doing what I've been doing? Thanks in advance.