I have an 80g system, 40g cube DT and a 40g sump/fuge. My tank is full of zoas and RFA's and I feed a bit on the heavy side. My water goes to a sock, thru the fuge with chaeto and a few inverts and then to a chamber with the skimmer and the return pump. I run my filter sock until it almost overflows which takes 5 to 7 days. Some people 'whine' about what a pain it is to change socks. But I think it's pretty easy and I don't have to do it as often as many here say they do. When I had a 200+g system I used 2 socks so changing was still basically a once a week operation.