Kipass4130, I have been using my Remora for 3 months now with no decline in efficency. I also have a few friends that have used them for a couple of years with no problem. They say they are good to 120gal, I like them but don't think they would be good on bigger tanks. 75 or smaller and I bileive they are great. The AquaC skimmers don't require any adjustments just periodic cleaning. It works on a water injection system to create foam. The only thing you can do is raise or lower the collection cup to achieve desired foam.