Hi grnmtnlwrdr,
I'm glad your willing to learn, after you get a grasp on the basics of filtering and the nitrogen cycle it's a rather easy thing.
This nest statement is not supposed to sound sarcastic so don't take it that way...There is a search function at the top of the page, go to advanced and search for Wet / Dry, wet dry, wetdry, W/D, filter and any iterations you can think of. Then go to the DIY section and do it again.
There is a wealth of info here and alot of people to help with it. Just do a little research first.
Trying to answer your questions before you do some reading would just be an injustice to you. Like telling you there are sumps, W/D's,submerged filters, refugiums and that they are all similar

without you knowing the basics it gets confusing
fast.
Here's a link thats a little technical but...
http://www.biofilters.com/webreview.htm
and
http://www.thetropicaltank.co.uk/cycling2.htm
My favorites file has over 1.5 gigs of links and thats just the aquarium / fish stuff. So save any info you find interesting for future reference.
Remember when you have questions, just ask.
Dr Joe
.