Great diagram, chris17! That's basically what my fisrt picture tried to be...but since it's a hob fuge, it's behind the tank, instead of beside it. I'd rather have it out to the side so I can see what's going on inside---but space it rather limited. But everything else looks the same: The pump will be mounted high in the display tank, flow through the fuge, them I'll drill a hole in the face of the fuge and plumb it with pvc so it will gravity feed back into the tank. I don't really trust the siphon design---too much could go wrong. This design is just like my aquaclear 200's I use on the tank now (just on a larger scale), and those work great. Thanks for all your help. I'll post pics as soon as I get it up and running.