I have a 55gal setup at work that I am considering for an octopus tank. Right now I am just trying to do some research and had a question about powerheads. Presently I have a Hydor Koralia Evolution powerhead at one end (I believe it's the 750gph model)...would this powerhead be OK or do I need a different one? Or do I need one at all? I just don't want it to get its tentacles caught up in the powerhead. I have an overflow box which I will be covering the top and a 20gal sump with a wet/dry and skimmer. Would that be oxygenation enough without the powerhead or do I need both? Do people use any kind of airstone in their tanks? I would think the octopus would pull it up/around by the airline tubing. Thanks!