On my 20L since I am running a filter sock now and I have less gph going through my sump than I used to with my bigger tank. The big baffle I use for a sponge/filter pad isnt really necessary and the water isnt flowing onto it enough to really catch much, only on the very edge. SO I was thinking maybe put some eggcrate in the bottom and make it a fuge slot? What do you guys think? I guess I would just need to make sure my water level was always up and not slack on top off's. Maybe ill invest in a ATO. The piece of glass thats close to the return is about 1/2" up from the bottom.