Well first off how many gallons is your tank, and is the UTH you have the correct size for the tank you have? Second of all it may not be the brand at all, what do you have your tank setup on? If it's vented than the heat cannot reflect to heat the tank properly. If this is the case you can try putting a tile under the UTH, or a piece of glass, or reflector tape which looks like tin foil. These are some items you can use to try and get your temp numbers up. I don't think you need to change brands, but someone else might know more than me on that subject. I personally use a Reptitherm Under Tank Heater (10-20 gallons) 6" by 8". Hope this helps