Sump question

[gill again68]

Ok, I just lost a sump (glass sump) due to what I think was acrylic expanding and cracking one of the sides of the tank. So I have decided to build another tank. I am using a 40 gal breeder as the tank and plan on purchasing glass dividers from a local glass shop. I want to put a refugium in this sump and wonder what the issues would be with drilling the partition that separates the refugium from the return. I would install a bulk head and possibly have 2 bulk heads to allow the flow off of the refugium. I just dont want the water to pour over the wall. I want to keep critters such as snails and so forth in there as best as possible as well as macro algae. Please give me your thoughts. I am pretty set on building the sump out of glass so whats your thoughts on the drilling and bulk heads.
Thanks in advance for the thoughts.

 

[eric b 125]

what do you want to accomplish with the holes?

 

[gill again68]

Well, in the acrylic tanks that I have seen the flow out of the refugium goes through a set of "teeth" cut into the top of the baffle. The holes I propose would be at surface level to draw off of the surface and help reduce any scum build up. Other than that the water would simply flow over the top and I guess that wouldnt be such a big deal. May be trying to over complicate it. You tell me.