Welcome to canreef!
Looks like you have tons of great advise to digest already, so no need for me to add any. There are already a couple of "newbies" just starting up, so read their posts as well.
300 gal plus sump, wow, you're off to a great start already. We only wish our tanks were that large. I can just imagine what I can do with 300gal, and HOW MUCH I can personally blow on my credit cards
Good luck.
Lenny.