Padz: they've all got good points but you're going to want lots of bubbles. Maybe two big stones in ten gallons fed by a thirty or more gallon aquarium air pump, enough to give you a fine screen of air bubbles to the roots. The rising air will circulate the water but there is a school of thought that a small fountain pump, even if it's just laying on its side will still circulate it better. With both of them going it's pretty hard to go wrong. HSA