I have a yung dovii that is about 2" right now. The temp. on the tank has always been around 79*-81*. After feeling the water and how cold it feels, i put another thermometer out of another tank and it is 72*-73*. The i used a meat thermometer and it has 75*-76*. What am i to do? the water dose feel cool, and the dovii seems to be doing good and eating good. What would be a good thermometer thats not to costly? im usinging Temp. Alert right now, but it is not right im afraid. thanks