Bobby, you are defeationg the purpose of bioballs by submerging them. The idea is to have an area of very high oxygen content so that the bacteria on the bioballs will stay at a high level of metabolism and thus eating as much waste as possible. There is about 7 ppm of oxygen in saturated seawater, there is 21% in air. That's a difference of 30,000 times the amount of oxygen available to the bacteria.

Gary