I have 3 AC500's that I got back in either 91' or 93' and they all work perfectly today and have been in use since the first day. I think they cost me $35 each....I have 12 Aqua Clears of various sizes that have been running for at least 10 years and 4 or 5 for 15 years plus....continously other than cleaning of course. I think I might have changed an impeller or two.
I have one extra thats never been opened or used....