Wow, I have just set up a 215g double overflow box fish only sw tank, I have the 300g pro clear aquatics w/d system and also using a twister UV both on the 2400 gph magnetic drive pump as well as an ets evolution 500 skimmer with it's own independent 950 gph magnetic drive pump. I too have never used a w/d system before and I have read sooooooo many sites about this system to better familiarize myself with it. I have a question though, reading all the thread advice on different sites I have begun to think that the blue bio balls should be replaced with live rock in order to not have your nitrate readings so high. Any inputs on this? I don't like live rock, it's my experience from previous tanks that led me to veer away from using it because of the massive takeover of bristle worms to which won the battle in the end, long story. I do however love the live sand and have about 2 to 3 or perhaps even 4 inches of it as my base.....depending on where you look in the tank as I have a blue spotted jawfish and a white orange spotted blenny that go to town sifting my live sand. After reading various sites, I have also just hooked up a small canister filter, it just sits next to my sump and cycles the sump water, I wanted to add some carbon and various filter media to ensure more clarity to the water. I love my setup but it looks a bit overwhelming but I am confident (eeeek) that I have surcomed to nice set-up, it just looks as though flooding can be a problem if one of those tubes break, but my overflow has a pvc pipe that is high in the overflow box so hopefully not alot of water will crash to the deck if it happens.