heating water for water change

I got lucky--My pump is big enough that when I mix my salt water the night or 48 hrs in advance (30 gal Brute Can) the pump brings the water to a perfect 78 degrees--No heater necessary.

 

My recommendation of heating the water first was to insure the salt was able to be totally dissolved because I thought the person wanted to use the water immediately, or, soon. I do realize if you add salt to room temp it is not as good (dissolving wise) but they are trying to avoid buying a heater.

 

Salinity levels also vary with temp. 75 degrees is optimal. There is more to it, but when you are "making" your water, it will take more ( or less, I forgot what way it converts) if your water is colder.

 

Fact is you don't need a heater with that kind of water change. Yes, the overall tank temperature will drop a possible 2 degrees, maybe 3 tops. Which will only last for about 30 minutes before it is brought back up. Unless you have some extremely tempermental specimens, this will not cause any harm at all. (We've all seen tanks drop temperatures to the 60's, or heat up to the 90's in a period of a couple hours- with often, no ill effect as long as its returned to a controlled temperature).

I've never heated up my water change water- and have never had any problems, if it is sitting at room temperature, it will be warm enough to be used for a water change, barring you don't live in an igloo or somewhere near the south pole with no furnace at hand.

If you are still really contemplating if you are safe to do this, try adding half your make up water right away, then wait 30 more minutes, and add the other half... keep an eye on your thermometer; you'll likely notice little change in the temperature.