I‘ve had an Eheim 2213/classic 250 for 6-7 years. It worked like a charm in my 29 for years. It started losing its flow. I’d clean the canister a every 3-4 months. It would get better, but not great. I finally cleaned all the hoses and replaced the impeller ( or propeller). Couldn’t believe the amount of gunk that came out. Soaked the tubes in hydrogen peroxide and scrubbed. It is incredible again. Maybe just needed to clean the hoses. I was about ready to add a sponge filter. I’m a little slow. It’s nice when a plan comes together.