What about adding a lid to the overflow box where the slots match( of course drilling a hole in the lid so the suction tube can enter the box) - then the box would work as designed ( the same could be done with a pvc cap on a uplift tube of a drill tank).
Image include of my thoughts
ok here is the overflow I had built into my tank .
Now when the Bio is a baby I will lay needle point backing over top of the egg crate ( and remove it when he/she has gotten larger).
Now again this is all in theory (I need to build my stand still , cycle my tank for at least four months ).
But I thought I would post it for future ideas for people - I think it should work pretty good.
PS. my over flow is based on this design ( just done internal ) http://www.nautilusreef.com/html/hibo.html
- so it has 0 teeth.
Here are the pics