Buy a protein skimmer. AquaC - Remora is a good protein skimmer.
Protein Skimmers are much more effective than the filter pad you have
in there. The stuff that's settling in the bottom is most likely
detritus, which is leftover food, die off from rock, etc. Suction this
out when you do a water change. also you might add some live rock
rubble in the sump for little creatures to live in. These creatures
will live by themselves by eating the leftover food, etc from the
water. Hope this is what you're looking for.

KurtG wrote:
I have a sump setup, but filtering is limited to something that is
fluffy white and looks like polyester batting and then ~40 bio balls.

I'm thinking of adding a better filter. My closest LFS (Petland) didn't
carry the fluffy white filter, but had a row of filters with clever
replacement cartridges. (I also noticed their prices where 50% higher
then online.)

My sump has a layer of yellowish white junk on the bottom that I can
stir up easily with my hand. Should I drain the sump as part of the
monthly partial water change? How do I get rid of this stuff or need I?

--Kurt