Lol, you and me both. I've never had a sump before so I'm really clueless. Maybe the tube isn't exposed to air on either side when the flow stops? That's what it sounds like at least. You use an airline tube to establish the siphon with all pumps off, then pull the tube out. I've read all the material they sent but haven't had a chance to actually play with it yet. I got the silencer just so I'd have it if needed (they give all of your money back for it if you don't need it) and that contraption looks very interesting! I spent some time today reading the plumbing chapter of my reef book and I'm still not positive on what materials to use to hook it all up. The lifereef directions make it sound like you use vinyl tubing but I've only seen people using pvc. I've only seen underneath a couple tanks, so I know nothing. I also need to decide on a return pump. Big enough and quiet.