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Having trouble with my filter making weird noises, sounds like an airlock issue. It's a Fluval 307, been running for about 6 months. Tank is 40 gallons, stocked with a few tetras and some Corydoras. Water params are good, 0 ammonia, 0 nitrite, 10 nitrate. Any ideas how to fix this?

Airlock issues are common with canister filters. First, make sure the intake and outtake tubes are free of debris. Check the impeller for any blockages too. Sometimes tilting the filter slightly can help release trapped air. Have you done any recent maintenance on it?

Yeah, airlocks can be a pain. I've had this happen with my Eheim. Try priming it a few times to force the air out. If that doesn't work, you might need to disassemble the filter and check the seals. Also, make sure the water level in the tank isn't too low.

universitykid wrote: ↑Mon Jun 16, 2025 9:11 pm Airlock issues are common with canister filters. First, make sure the intake and outtake tubes are free of debris. Check the impeller for any blockages too. Sometimes tilting the filter slightly can help release trapped air. Have you done any recent maintenance on it?

That's solid advice. I'd also add that running the filter dry for too long can cause this. Maybe double-check the priming process in the manual.

Had the same issue last week. Took the whole thing apart, cleaned the impeller, and it's been quiet since. Might wanna give that a shot if nothing else works.

Thanks for the tips, everyone. Gonna try cleaning the impeller and tilting the filter first. Will update if it works.

Lacuna wrote: ↑Mon Jun 16, 2025 11:00 pm Had the same issue last week. Took the whole thing apart, cleaned the impeller, and it's been quiet since. Might wanna give that a shot if nothing else works.

Yep, impeller issues are often the culprit. Also, if you're using a spray bar, make sure it's not clogged. That can cause weird pressure changes.

Another thing to consider is the O-rings. If they're worn out, they might not be sealing properly, letting air in. Replacing them is cheap and easy.

Good point about the O-rings. Also, if you've recently moved the filter or changed the tubing, there might be a small leak somewhere. A bit of food-safe lubricant on the seals can help too.