[Funky_Fish14]

You can still drill lines into the bottom on the far end (opposit the overflow) without risking the use of check valves.

How do you get away with this?

- From the underside where the return goes in, as you go back toward the overflow, you bring the 'return line' back upward to above the waterline in the aquarium. (do this with any associated lines run in such a way). From a point above the waterline, drill a small hole in the line, and have a hose running spraying a small amount of water into the overflow box. (this water comes from the return line). What this does is that in the event of a power outage, etc... the pump shuts off... all the lines 'start' to drain, (because of a syphon effect), but this small line spraying into the overflow (left above the water) will empty quickly and allow air into the line, stopping the syphon, and preventing any floods or tanks draining.

Presto - no risky (total crap IMO) cheque valves, no tank floods/drains, no return lines visible above the tank, no powerheads, and no closed loop.

If you need a more detailed description let me know. If you want help building such a set-up let me know. (or with any plumbing). You will need to accound for head-loss from the upper loop that prevents the syphon. It is easy to make a very effective assembly like this.

Cheers, and hope that helps?

Chris