I actually have a thermometer that sticks onto the inside of the tank with a suction cup. When I am doing a water change I just pluck the thermometer out of the tank and take it to the sink with me. I add my drops of conditioner to the bucket first so I don't forget and so that it will be thoroughly mixed when I fill the bucket. I then use the thermometer under the running tap water and adjust the tap water to exactly the same temperature as the tank. Then I fill the bucket. Then it is back to the tank with the water. I'm really new at this, but this seems to work for me.
