Getting an old acrylic predrilled and need help with plumbing.

Was wondering if I could get your input on how to do some plumbing.

I just got a 80g tank that was once a part of a LFS central tank system. It has two 1 1/2" holes drilled through the top near the back wall and centered. Then on the back wall there are two 1 1/2" holes drilled, one in each top corner.

I would like to use either my 29g AGA or my 55g AGA as a refuge under the tank. Mainly to hide the heaters and filter ( I have an XP3 now but may add a used Ehiem as well.) Also since the larger water column I figure I can overstock the 80g with discus(figuring it would be filtered like a 110 or 130g tank).

How can I work the plumbing?

I was figuring I would turn the two holes on the top as return lines via a large powerhead or pump. And turn the back holes as passive overflows using elbow PVC pieces. But was wondering if that would be feasible since normally the intakes are near the bottom of the tank and the return at the top.

Also I would like to keep this as cheap and simple as possible.

Thanks in advance for any suggestions.

J

Thanks for the reply Nolapete

I had a feeling I was on the right track, and after your post and some searching on previous threads, I am pretty sure I am.

The plumbing is pretty straight forward, so I don't see any problem there, but one question (which I wouldn't of thought of) arose.

If I have two 1 1/2' overflows, how big of a powerhead / pump should I use to carry the water up to the top of the tank (figuring, but not sure since I haven't built a stand yet) about 4 1/2 feet.

Thanks again in advance...
Jason