I run a skimmer on my prop system, though many people dont. Mines a BB sps frag tank though so a skimmer is thought of as the way to go. I read your other post and you were considering to go BB too. I love the BB idea, but just for frag tanks. I do however have a fuge attached to the tank with LR and chaeto, which I read may be the path your going to take. My tank is a shallow 36X25X12, and the sump is a 40 breeder, which allowed for a rather large fuge. Your gonna have to squeeze in a lot of stuff into a small, looks like 20g, sump. Don't get me wrong, many people have this size sump and like it. With a skimmer and a fuge in a 20 gallon your gonna have to replace evaporated water regularly. But it can be done! Check out melev's webpage for sump plans or read some posts. Post some more pics as you get this going too.