How much air should be in the canister?

by Paul Glazik
(Allen, Tx USA)

I have the Rena Filstar XP2. Although all the hoses are tightly connected, a pocket of air forms in the canister that occupies approx. the top 2.5-3 inches of the canister. I have not noticed any loss of flow pressure from the return but occasionally the filter makes a loud sucking noise and then clears some of the air into the tank. Is this normal?
A: No, please read through the FAQ's already posted. It will take some effort but this question has come up before and has been answered many times. Somewhere air is leaking into the system on the intake side.