What exactly is a closed loop?

[mrpope]

I want a SCWD but I dont have a sump so I cant hook it up to a return pump. I was wondering what closed loop means. Ive seen it mentioned here before but I still dont get it. Is it by using an external pump, or submersible one. Ideally I would want to run it with an external pump and have the SCWD outside the tank, so the only thing you see is an inlet tube and two return tubes. Any thoughts? Suggestions?

[grimlock3000]

http://www.melevsreef.com/closedloop.html

[mrpope]

thanks

[mrpope]

Thats a great idea, but could I incorporate rubber hose intead of pvc on the scwd outlets? I only ask because my hob fuge stcks out pretty far and I would want to sqeeze the hoe behind it ( but not to pinch closed)

[fishfreek]

You have to use hose on the scwd as the scwd has push on style connections and as far as I know there are no PVC accepting connectors for this. I converted my PVC pumbing into hose tubing to connect the scwd by using a pvc to hose adaptor fitting. then using hose and hose clamps connecting the scwd and the pvc together with a short 6" section of hose.