I have filter floss in the 1st chamber, used to have Chaeto with submersible led light in the 2nd (now have MJ for the chiller), ATO floats in the 3rd, Return pump along with return hose from the chiller which empties into a bag of carbon and phosban. The floss gets changed out 2X per week and is re-usable if you get the good stuff in the plastic bag. I have the vent holes all blocked off with outlet covers, upper "teeth" filed down about 1/4" along with a old credit card glued to the back side all to get good surface skimming so there is no slick on the water surface. It is in my office in clearwater if you want to check it out.