A few weeks ago, I bought a 55 gallon setup for $80. Some of you might remember that it included a high end canopy and stand (I think it's old style Oceanic), Little Giant pump, wet/dry filter, and a bunch of other stuff. Well, in the bunch of other stuff was an Aquaclear 500. I figured that based on how dirty it was that it wasn't going to work. Tonight, I cleaned it up and set it up on the 90 gallon as the 4th Aquaclear 500 running on that tank. Now that it's clean, it looks and runs like a brand new filter!