The only LFS in Brampton is unfortunately Big Als on Kennedy.
If you have to go in there, ask for Randy. He is the only guy I have ever dealt with- good guy, knows his shit.
I personally go into Mississauga- it's worth the drive.
Canada Corals is the closest to Brampton and has pretty descent selections of dry goods and corals....lots of quality stuff and strictly devoted to reef aquarium not to mention nice and knowledgeable people like Dan and Isabelle.