Sounds like the box then.

It just surprises me that the box at 5x5 would restrict the flow that much.

Call me if I can help.


Wendell

Are the boxes 2 sided corner overflows ? or centered 3 sided ?

Im guessing the spacing between the teeth is the problem.

They wouldnt happen to be a "saw blade" width slots would they ?

Fudge, the teeth are 5/16" and the box is 2 sided. I have fixed the problem and now it works fine. I have used a high speed rotary saw (big dremel) and cut the top of the box off 3/4" below the bottom of the teeth. I then glued the removed L shaped peice to the outside of the box. This lowered the top of the teeth 3/4" and provided an extra 1/2" of lip length per box. The extra 1" total lip and the lowered box height seem to handle the flow now. For those looking at adding boxes to their tanks I can say that the calculator on reefcentral for overflow length is a good starting point. It recommends 23" of total overflow length for 1500 gph. I had 22 and the water was just cresting the top of the teeth. I now have 23 and the flow is just below the top.

http://www.reefcentral.com/calc/drai...0&drain=Submit

Thanks for all your help and tips. :biggrin: