Thanks and everyone else for all of the replies. I think I was over thinking it and thought I needed more watts than I do.I use two 400W heaters in my 450, in the sump. With all of the equipment, you will likely see it sustains temps on its own pretty well.
I'm in southern California and leave windows open most days, so as you mentioned, with other equipment I might not need heaters. I'm trying to keep as much equipment out of the sump if I can to reduce temps because my biggest fear is having to buy a chiller.