Hey so I'm having trouble keeping my feeder crickets alive. I have them in a cricket keeper cage which has plenty of ventilation. I have flukers orange cubes and was recommended gerbil food with alfalfa to help gut load. The tank was just cleaned (with just warm water). I got a new batch of 50 half inch crickets and over night I found many dead ones. They have been cleaned out already. The temperature is in the 60s where I keep them which I was told was too cold so I bought a uth. After I got it home and opened I realized it's not meant for plastic. Could it be the temperature that's killing them? If so is there anyway I can use the uth heater without melting the cage? It's the zoo med reptitherm mini uth 4w.