Two questions here:1. I was thinking of using some lava rock bought in the bags from Lowes as some bio media for my two xp4's. Any thoughts or suggestions? 2. I have an AC110 on a growout tank. After the fish are moved, I would like it house a single flowerhorn. Right now, I have the pads on the bottom, 4 bags of the small ceramic rings, and the ammonia absorbers on top. Any suggestions on how to add more to handle a large bio load? More rings? Also, no chemical filtration is being used, your ideas and thoughts.