I had to go out and purchase a new filter for my 20H today. I've had Tetras in the past, and they are tricky to take apart, clean and reassemble correctly.
Aqua Clear was my first choice. I went to Pet Smart online, and the filter I wanted to get was 18.88 - in store only.
Unfortunately, the local Pet Smart did not carry this filter... it is no longer being made. Looks like Fluval 'ate' Aqua Clear!
The good news: although I had to spend a little more than I had planned, for less than $30.00, I was able to get the Fluval/Aqua Clear 50. This filter is for tanks 20-50 gallons, and the output flow is adjustable.
It is nearly silent, except for the sound of the water (return outflow).
This tank is in the bedroom currently, and we couldn't be more pleased.
Hope you find a good filter for your set-up!