What are you putting in the tank?
Although people usu. think of a wet/dry filter as a seperate unit, with sump, pump, etc. This is not necessarily true. A penguin biowheel system is a wet/dry filter as well & is less hassle to use. PS - I've heard good things about the Penguins but this is prob. too small for 100
gal - canister filter is a better choice. Marineland also makes biowheel to fit canister.
I would go the wet/dry/sump route only if you are dealing with lots/messy fish ... eg goldfish. I would suggest reading the saltwater posts as this is more commonly used in
SW & the info is just as good for
FW.
For myself, I have an 80
gal with goldfish. After much research decided on a
DIY wet/dry/sump. I used a 30
gal tub as my sump & made my filter basket, distribution pipes, etc. I have 1
gal of bioballs as my media, although I have capacity to go up to 5
gal as stocking increases.
Size of sump - bigger the better, you are basically increasing the total capacity of your tank with this setup, may as well make it worthwhile <no point having a 5
gal sump - you may jsut as well go with a biowheel >.
Pump - no personal experience with brands - as I am using a Magnum350 as my return pump. Recommended pump capacity is 5 water changes per hour - ie. 500
gal/hr in your case. <OK I am below the recommendations in my set up at 350
gal/hr, but I got the canister cheap used & it is working out fine for me...
>
I find this series of articles useful:
http://reefkeeping.com/issues/2003-01/gt/index.htm
http://reefkeeping.com/issues/2003-04/gt/index.htm
http://reefkeeping.com/issues/2003-07/gt/index.htm
Also try sites like this:
http://www.cyberreefguru.com/diy/index.html
http://reefcentral.com/