I need a super fine mesh or sponge to provent kuhli fry from getting into my home made canister. The problem is it has to be something that won't impede flow. I have a very fast flow rate pump attached 3200gph it's running at nearly full capacity. The baby loaches are somehow getting through the overflow and prefilter past polyfil, floss, and fine poret foam. They seem to be doing fine living inside the filter but it's becoming a nuisance having to open it every night and remove them.. I was thinking of cutting a few filter bags and layering them around the intake in the overflow. I'm just not sure if this will restrict flow. Any recommendations on some super fine mesh that won't restrict flow and hold up? I tried attaching a little "pvc chamber" filled with a snug fit cut out of poret foam to the inside of the bulkhead but they got through this.