I’ve been rehabilitating my pond with aeration via a HiBlow XP80, 100′ of PVC, 60′ of weighted airline and a diffuser. I needed to know if I could step down from the 3/4″ PVC to 5/8″ weighted airline the final 60′ to save some $$$. Mike was very helpful, he provided me my estimated friction loss, PSI, and final CFM or L/min letting me know that my setup would work fine for my pond application. His responses were prompt and easy to understand. Mike saved me a lot of confusion on my part. Thanks Mike