Going from nano to large scale

[digi]

Hey all,

I've been running a nano reef in a 8 gallon display tank (20 gallons total w/ sump and fuge) for a little over a year... everything's been going well. I have been thinking of going with a much larger setup, but am wondering how things work on a much larger scale? Let's say, 100 gallons... There's a few questions I have.

1. First of all, how do water changes work in such a large tank? Do you guys do them weekly? 10-15% water volume? 10 gallons - 15 gallons each week is a lot of water!
2. Equipment includes: Powerhead, Skimmer, Lighting, Filter? Have I missed anything?
3. Do you guys use ATO's? In my Nano its pretty essential... I dunno about on a larger scale setup.
4. When is a dosing regime required? I am clueless about this topic... I dont dose.