well temperature will affect you SG or salinity reading so idealy you want the water to be the temp that you have your tank right so you the right amount of salt, im going to clue you in to a little trick of mine, 2.5 cups of salt in a 5 gallon bucket will mix the water to be at 1.023 no matter the temp aas long as you let the temp rise the salinity will br right on, so go borrow your mom's measuring cup and get mixing, dont tell her i told you to use her bake ware for it though, and best thing to do would to go out and buy one just for SW stuff because salt left in your cup isnt good for baking