my husband does the water change on my tank and dont forget it should only be 25% water change not all the water that way you should not have to use a kettle or warm water from the tap we just use straight cold water from the tap we have three fish tanks being doing it this way for awhile never lost any fish also remember to wash the filter in the bucket of water you just emptyied from the tank. but i dont know if this is write but it works and all our friends that have fish do it the same way. also a number of pet shops do it this way to and that what they told us to do.