Currently I have a 4' x 10' DWC raft bed and 12 55 gallon half barrels filled with rock. The media are divided with 6 constant flow and 6 siphon. I am thinking of turning the Media beds into a combination bed with about 10" of water space and 6 inches of rock on the bottom for the bacteria. Will this work, or do the bacteria need oxygen for conversion? I am tired of the individual small beds with each one having its own fill and drain system. Currently I have 4 barrel halves in each table (3 tables). I am wanting to convert them to one fill/one drain per table beds to make it easier to manage. Any thoughts/information?