Mike, I perused your calcs and they look good, but I think the "1.1 cfm at 30ft" must be the amount of air the pump will put out at a depth of 30 feet NOT the amount of water that it moves. It's just too small.
I know you know what you are asking for (lift rate), but I don't think your aeration company knows what your asking for.
OR the system is designed for a very small yard pond, but surely that is not the case since they spec it a 30 foot of water depth.
Also, for point of reference, Vertex shows with their lift rate chart that the volume of water that gets moved actually increases as the diffuser gets deeper. This is given that the minimum recommended amount of air flow is provided and other brand diffusers should be no different.
