Turtle Tank Filter Aquarium Filter w/ Detachable U-V Light for 30-75Gal, Waterfall Flow Adjustable Low Water Level Internal Green Clean Machine Killing Deodorization Saltwater Freshwater Crystal ClearSTAGE1 The detachable 254nm U V light efficient further diminishes odor and eradicates green water STAGE 2 3 CATCHES DEBRIS: Dense, DOUBLE SIDED(White&Black) mesh sponge clip filters out debris, fish waste, food residue, plant leaves and fine particles etc STAGE 4 BIO BALLS: These biological media system provide a large surface area and open porosity to absorb odor and discoloration and break down waste to improve water quality ADJUSTABLE &STEADY