If you get it set up and fill the tank up that much, will you not overflow when power is off? You should mark a high water mark while ON and OFF so you have a quick reference point for top-offs. Dont be fooled by the More is Better thought process on sump water levels, keep as much of your bio media in the air with free running water trickling over it for max oxygenation and bacteria growth. As stated before, bio media isnt as effective totally submerged as it is in a wet/dry chamber with the water running over it.