Now this is how my fuge is set up.
On the left side the half round circle the pvc goes down to the bottom. Witch leaves a half inch space from the end of the pvc from the glass. I then filled it full of sand and small rocks the rocks is to help the sand from clumping up. So this creates a lot of bacteria to go into and grow (like a fbf). The rounded part of plexi glass is higher then the one on the other side so the water flows out of it into the fuge. The fuge is planted full and has a deep sand bed with low light plants. It then runs over into the pump area to be pumped back up. Simple as can be
and the only reason I bent the p.glass was because I was lazy and diner want to cut it to make it go straight across
This has worked great for me but I also run a canister filter and a hob.