"Working in fish sales, I would recommend this product to anyone. I keep a 10g beside my bed and literally the only sound you will hear is the slight drizzle of water, like a fountain. You will never hear the motor unless there isn't enough water and even then it is very quite (I actually had one burn up because I didn't hear the motor running w/o water and even then it was a few days before I realized that the filter wasn't even on).
Not only is it quiet, but it also keeps the tank clean and clear. It filters on three levels: Mechanical, Biological, and Chemical (which is exactly what you want!). The sponge you only need to replace every 6 months or more (and then only if you can no longer rinse the stuff out). The carbon does require changing about every month, but it is inexpensive, comes in packs of three, and is sold everywhere. The biological filter almost never needs replacing (only when the porcelein begins to degrade, which took two years in my tank) and again is very cheap and can be bought in packs.
As with all filters, I would recommned buying a size up from what you have (ie, if you have a 10g buy a filter for a 20g) just because you can never have enough filtration, but even if you didn't I believe it would be sufficient.
All in all, I have had mine for nearly three years, bought them for my other tanks, and don't plan on changing anytime soon."