The last few days my Eheim canister filter has gotten louder than normal. Nothing in the tank has changed at all, but I did read that sometimes trapped air can cause the loud noise from the filter. I understand that there will be some noise, but this one is much louder than any before.
I have tried shaking the filter to try and move the bubbles, and that has worked for a matter of seconds before starting to make noise again.
There is nothing trapped in the impeller when I pulled it apart, but it still continues making the sound.
I believe there is still trapped air in the canister as when tilting and shaking the canister, the sound changes for a short period before returning to the original sound. Also, for a short period after shaking small air bubbles come from the spreader bar. However I do the same every few hours and air still comes out.
Am I missing something to do with priming the Canister? It is an Eheim 2213