Just an FYI, diaphragm type pumps have a performance curve that drops off significantly with back pressure. In other words, 160 lpm likely is the output at 0 psi. At the rated stall pressure psi the output is likely zero lpm. At pressures in between the flow in lpm (or cfm) will be intermediate. I have not looked at your second link yet, but if they have a performance curve (or can email or otherwise provide one) it is very useful information. For example, say you want to run your diffusers at 8' depth. That is about a 4 psi back pressure to the pump. So the pump output at that depth/pressure might only be 80 lpm instead of the advertised 160 lpm. If you can source a performance curve chart on the pump, you can see what the pump will put out for flow at the depth you want to run it. This will give you a lot better idea of the properly sized diffuser(s) to use.
