Huh, I've only had to replace an Aqua Clear impeller once when I let it suck up sand & it etched the ceramic piece. I love ACs & have for 25-30 years, maybe, like some things, their not the same anymore. My newest is probably at least 15 years old & still going strong but not necessarily in continuous use, I've lost track. I "hear" the new sponges aren't as durable as the old but I've never replaced mine, ever.