I have a 30 gal. tank, and have planned to use a 20 gal tank for my sump. However, I never bothered to measure the available space under my stand. I can make a 20 gal. fit, but a ten gallon tank would go much better (would have to alter aquarium support boards). So my question is a ten gallon sump too small for a thirty gallon reef ? Oh BTW the tank is already up and going.