Temp and Salt Water Questions

[LeanneP]

My tank is doing great again thanks to everyone's help on here. I am just wondering what temp everyone keeps there tanks at? and is a 2 degree fluxuation too much throughout the day? I have halide lights which as you know give a lot of heat. I have one fan and am just wondering if I should get another to keep the temp more stable. Right now I just have fish. If I add corals would the temp still be the same?
Also wondering how long people mix their salt water for-24 or 48 hours?
Thanks for all the help for the newbie!!
Leanne