Mysterious Eheim canister secrets

I had problems re-connecting my Eheim 2217 when I cleaned it for the first time. I had kept the leaflet that came with it. I took out the canister, emptied it completely and followed the instructions word for word. It took maybe 10-15 seconds to push out any trapped air and was quiet again. I do the same procedure as in the leaflet ever since and never got a problem. Its so silent you won't know its there. I have to look up through the tank at the surface agitation to make sure its working.
 
Some pretty good ideas there. Especially the one-sock wolfman. I can't quite figure what difference suction to start might make when I get it running otherwise but I will give it a shot. There is also definitely back pressure on my system. The returns are convoluted and my DIY spray bar has fairly small holes, this might solve my problem also I'm guessing. Come to think of it...getting it running without that back pressure first and in fact using the afore mentioned suction technique will in fact be my next assignment. Wow...I think Im actually optimistic.
 
Make sure you are not getting any air bubbles into the canister through the uptake hose. Even very fine bubbles generated by an airstone or by the return, if sucked into the intake, will eventually aggregate inside the canister and cause noise. Sometimes the extremely fine bubbles are hard to detect. Depending on where the output from the canister is pointed inside the tank, some may be directed toward the inlet, get sucked in, and cause your continual problem.

For my 2222, rocking the canister back and forth and side to side will displace all the initially trapped air. I check it periodically for trapped air, though rarely do I find a buildup, since I keep the inlet well away from the air wand and the agitation caused by the canister's outflow.
 
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