My air pump for UGF on a 20g tank (established for 4 years) has given
out. I would like a quieter option and have been looking into other
types of filtration. I am considering pulling out the UGF and replacing
with a power filter of some sort with the aim of finding something
quiet, economical, and easy to maintain. The fish load is light and
there are some live plants (certainly not thriving, though). My
questions are (1) should I pull the UGF (or go with a powerhead (trying
one now and it makes a racket), and (2) if removing the UGF, what kind
of filter to go with (eg, is a bio-wheel necessary in a cycled tank
like this if I keep the gravel)?

Thanks for your input.
-Barry