In regards to the bio balls:
It is hard to tell, but the overflows are only 1/3 full, the bio balls are there to oxygenate and to silence the crashing of the water.
The way things are designed, I am able to fully fill the overflows to flush the bio balls into filter socks below. There shouldn't be a problem, but if so, I can look at things later.
Thanks for the advice everyone, keep it coming....
Any ideas on how to cover the bottom?