the only time I've ever had new SW
that's aging precipitate the calcium was 2 weeks ago, when I had the bright idea to pre-dose the new water with calcium and alk
For the record, I don't do any heating of top off water. Consider that its often close to room temp (70 degrees) and that you're probably only adding 1-2 gallons to at least 20 gallons. you're talking about changing the temp of the tank water about .1 to .2 degrees. who cares?
now for a water change, yes age the SW
, and yes bring it up to the same temp.