Hey guys I'm going to be running a fluidized bed in the center chamber of a sump which is going to be roughly 21 gallons(34.5x13x18) I plan on having an air stone/diffuser on each end of the chamber. I was thinking 2 12 inch diffusers one on each end. They will be circulating 75 liters of kaldness. Can anyone recommend a good stone/diffuser that can push enough air to circulate the media. I will be running an AP 100 pump with a 2way gang valve to regulate even flow to both ends of the chamber. Thanks in advance