Originally Posted by sainthogan
I like to let it sit just to get it to room temperature. The water where I live is highly unpredictable and fluctuates from freezing cold to scalding hot with just a nudge of the faucet handle. This way, it won't be too hot for Fishy and it won't be too cold either that she goes into shock before the heater can warm it up. I keep my room on the warm side anyway, so there isn't too much of a temperature variance between the new water and her tank water.
^ exactly what I do as well. I'll usually fill a bucket with conditioner and let it sit for a couple of hours before doing my water change. The conditioner works instantly, but I don't trust the water temperature coming out of my faucet.