From the research I did, for fish only it's anywhere from 1.019-1.022, for corals it's 1.023-1.025. I have fish and corals, so I usually keep mine 1.024-1.025, and from what I've heard from others, that's a pretty common range. Yeah, I think most marine fish have a temp range from 72-78* F, so 70 is a little cool for them. My tank runs 78-79, depending on if I have a/c on or not. you're in Alaska, right? Are you in one of those areas I've heard about where everything has to get flown in cuz the roads are scarce? Lol. Not trying to stereotype Alaska, just heard that on a Discovery channel show or something. Lol.