Thanks for all the input guys...

tex, i would definantely foam the overflows before siliconed to the aquarium. The trashbag idea seems like a pretty good idea.

Ace the columns i was thinking of having constructed would be round rather than rectangular. So I didn't know if it would cause alot of problems cutting teeth around them. 2 column would be strictly drains (left 1/3 & right 1/3 of tank), then the 1 center column would be strictly a return with directional outputs using locline along the top. My thoughts were the columns would be pretty easy to hide and make nice rock ledges and formations. I need to figure out the diameter of the cloumns maybe around 3" dia.

The island overlow box was my original plan, but they're usually pretty big and take up quite a bit of space since I would need at least 3 holes drilled. The footprint of the tank is not really that big since it's a bowfront.

Ray