This problem was alleviated by placing backing in between the two tanks. An essential part of any fish hobbyist is a thermometer. A thermometer should be kept in your tank at all times so that you can monitor the water temperature. The other time you will use your thermometer is when you are refilling the tank after a water change. It is important that you put the water back into the tank at the same temperature as the tank is currently at.
Thermometers are very cheap.
There are three types of thermometers on the market. One is a strip type thermometer that sticks to the outside of your tank. These are not very good and are very hard to read. This is the first type of thermometer we purchased. We quickly replaced it.