Is your 100' in the water or running to it?

I have approx 100' running in 3/4" pvc from the pump to the pond edge at a T and then two 100' branches of 3/8" weighted tubing going to each diffuser. Works great.

The air volume and pressure for these systems is so low it doesn't require much. I push 20+ cfm though a 100' air hose in my shop at 175 psi.