We timed how much time it took for each air pump to vacant a liter of water within the bottle. Due to the fact a liter of air displaces a liter of water, this gave us our move rate in liters per minute (LPM), which we then converted to gallons per hour. I've a 220 L tank 900mm very long, 500mm high and 400mm deep. I want to operate a sponge filt