Your not going to like what I say but Here it is. Don't use an air pump at all. Use water surface agitation. Waterfalls, fluming any type of water movement. Air pumps don't put air in the water they agate the surface of the water allowing for o2 to enter the water through the atmosphere. The same that waterfalls and fluming do. Our atmosphere contains O2 and CO2. Air pump agate the water but they also introduce CO2 also. Leaves love CO2, but roots hate it, roots love O2, but leaves hate it. So if your tired of chasing your PH up and down the street, and the heat your blowing up their ass, and the nice humming, oh don't forget the expenses of air pumps. When I look around in nature I don't see any air pumps. Just the wind and the physical movement of water. Just a thought, I could be wrong.