I just cleaned all the filters on all of my aquariums. In December I put a Fluval FX6 on my 125 gallon aquarium and haven't had to clean it until today. It wasn't all that dirty, I could have went a couple more months without cleaning it. Not to bad considering I have at least 40-50 Cichlids in that tank. I do have a Magnum 350, a Fluval U4 and 3 large sponge filters on that tank also. The Fluval FX6 is by far the best filter I've ever had.