[HenryC]

This next part was what took a little convincing for me. I have loved the diffuser type bottom drains since I first retrofitted my existing drains. The new pond will not have diffusers on top of the drains. Instead, there will be 2 air pits in-between the 3 bottom drains. Once again, these will provide no projections into the pond. Inside the air pits will be large air stones. At 8ft depth some people have reported problems with super saturation caused by the pressure required to force air through the rubber diffuser membranes at that depth. Hopefully, these air stones will not cause the same effect. Below is a shot of one of the air pits. It still needs some more work to smooth out the top and counter sink any SS screws. The air stones have not been installed yet either.