I've been through several different diy overflows, and am tired of worrying about them when I'm away from the house. My current one only allows me to open up the mag7 return pump about half way, so I'm thinking its only returning about 2-300 gph. So, I think I'm going to break down and ordering a cs90 overflow box from marine depot. I'll probably double that flow and gain some peace of mind. Any input on the cpr continuous siphon overflow boxes? Most of the reviews I'm reading are pretty good.