Yeah, the problem did turn out to be air trapped in there, but it wasn't the O-ring or anything, just the air left in there when I refilled it. I just started filling the canister up, putting the top on and pouring some water in through the inlet, the tilting it a bit for the air to escape from the outlet. I repeat that till I have no more air pockets in there, and the water level is actually up to the valves on each side. Then I hook it up to the tank and open the valves up. No out of the ordinary sounds since I started doing this.
Thanks for the advise though. Might have to use the silicone idea once the O-ring starts getting old.
Thanks for the advise though. Might have to use the silicone idea once the O-ring starts getting old.