Sump?

That looks good. The only changes I would make to it are where you drill on both the 5.5g and the 10g tanks. I would go two-thirds up the 5.5 and a little more than half way up the 10g.

 

+1, or just make your own PVC surface skimmer and siphon feed off of the 5.5. Really no need for drilling on something like that.

 

The holes should defenetly be drilled higher. That drawing was really only ment as an example, not a final draft. Only thing I don't like about using a siphon, is what if it fails? then your whole tank will be on the floor. Unless You use a pump to make it a continuous siphon. Works well on my overflow
Continuous Siphon Overflow

 

Yeah.....I would drill too. You could mod it with a aqua-lifter to hold siphon and that would work OK (unless it clogged)...but there isn't a lot of room in a 5.5 to compensate for declining water level in a 55 in case it failed for whatever reason. The dual 10s would be able to prevent an overflow if things were set up correctly.

 

Pharmr you are 100% right. But I just had a crazy idea(by crazy I mean very difficult to diy but could be interesting). What if he didnt drill the 5.5, instead fab some kind of legs to have it sit directly in the center of the return tank but elevated about 3/4 the way up. Then just have the water overflow over the top of the refugium on all 4 sides into the return tank. A eggcrate top would haft to be installed in the top, to prevent the chaeto from falling into the return tank, hahaha. It would sound like there is a waterfall under your tank, but may have a sort of peaceful rainforest type of sound. Would probably look pretty cool. But again, not very functional and would require some tricky plumbing. I have a few better ideas, but I think I will try and draw them out tomarro.

4phish, If you post up how much room you have to work with, and maybe some pics. Then we may be able to suggest something better.

 

Thats an interesting idea Infantry. I'm not sure how easy it would be to get the 5.5 level though so the water evenly overflowed the tank. It would be easier to put the 5.5 at a little angle so taht the water intentionally overflowed one end. It also sounds like it might be a bit on the loud side and my wife would nag me about it until I fixed it. According to her "Loud splashing water isnt soothing at 3 AM!!!"

 

hahaha It was just sort of a idea that just jumped in my head. Would be more for looks, than functionality. I have a decent idea in mind, but I need to take some measurements and sketch some things first.