Your bioballs and other bio media work better if they are not submerged. The water needs to trickle through them and get aereated as well. I am in the process of setting up my 90g and I will post pictures of all of it. 45g sump, mag 950gph, two overflows, 1 split return, 2 biotowers.. I am using cheap DIY stuff.. no bioballs, they are too expensive for me. I am waiting for my bulkheads to arrive and my father in law to get me his hole drill.