I know reptivite has both calcium and d3, but it's not suitable singly. You do need to supplement with a calcium and d3 only powder as well. I don't know about the fish and snail, it could pose a parasite risk? Someone else will need to chime in on that.
As far as your water, if you were previously not treating water for misting, this could also be a problem. Godd you're treating all of the water now.
Everything else seems fine....