I have four SunSun HW404B filters, and one Fluval 306.
I bought the Fluval first, and you can tell which ones I liked better.
One of them... naturally the one in my office, is getting louder. Substantially louder -- from almost dead silent, to now being audible over my computer (which I sit next to), and actually audible from the next room if it is quite. It was nowhere near that noisy before.
I recently cleaned it thoroughly, including the impeller, added some lube, then finally replaced the shaft on it (ok, I broke it while cleaning it for a second time), cleaned the impeller, cleaned the impeller recess.
What makes a canister hum when it didn't before?
I've twisted it, shaken it (it's not air), made sure it is not resting on something that would amplify the noise like a cabinet side. The noise is mostly hum, not water movement.
I've never opened the casing for the motor itself (not even sure if one can, I know some pumps are encased in epoxy for safety reasons, have not looked). Not sure if there's anything that can become loose in it.
I've turned off the UV
light (in case it was a separate transformer to power it) and no impact.
So what makes a canister hum? And any suggestions, other than swapping it out. I may swap for one in another room, though I kind of hate to move the noise there either.