I have an Aqueon Water changer and I have to say I was extremely disapointed with it's quality. I keep it outside which may be the problem, but the ball valves on both sides completely siezed up within the first 2 weeks I had it. I had to disassemble and give TLC to get them to move at all.
Second is minor, but if you use in conjuction with a water hose like I do, there is no way to adjust suction/flow except running down to the backyard where the spigot is.
Oh and the clear tube section ALWAYS falls off when I hang up the hose after use. Minor, but irritating that the substrate vacuum section is always in two pieces when not in use.
Also when adding water back in I am probably old-fashioned and possibly for no reason. I let the water settle in buckets and like to de-chlorinate before adding water to the tank. Does everyone actually refill their tanks with straight tap water and then treat? I know it's only a short time but I always thought chlorine was really really bad for fish and even if it was only poisoning them for a short time while I refill, it was still bad. Not true?