hi guys my son is away with the army and dad (myself) has been left with 2 ball pythons and 2 vivariums, i have never kept reptiles in my life only ever kept dogs , sorry to ramble on, my question is the basking side of both tanks is 90 f which i have researched and is near enough spot on, but my cooler end of the vivs are only around 69.8f which is to low, so my question is how do i get the cooler end to increase to 79f without getting to hot on the basking side , many thanks ,sorry if this has been asked a thousand times