If you havent bought the bio balls yet, you can save money buying plastic pot scrubbers from the dollar store. Just make sure they have no soaps added. They work just as well as bioballs. I also pull one out of my sump and scrub stuff with them. After all they are scrubbers LOL. Another good tip is to put an airstone in your sump under the biomedia. If you increase the oxygen to the media you will grow a stronger colony of bacteria. As for submerging the bio balls. Im not so sure. I think they need air to grow so you want them wet not submerged.