I use this a LOT with my tropical tank that is usually at around 80 degrees. I fill up about 8 1 gallon spring water containers with cold tap water( because the hot sits in the hot water tank and has harmful metals), I put them in the bath tub, and fill the tub up with all hot water. Let them sit in the hot water for about an hour, and you are good to go! Its much easier to keep the temp around the same for goldies or tropicals with warmer water, and it seems to make my tropicals much happier. Just add water treatment, and you are good to go.