Originally Posted by
reefkprZ
no its not true its an urban legend (or Myth if you prefer) , as long as there is water in the sump covering the heater the heat transfer of the water will not allow it to melt.
I'd wondered that too I have an acrylic tank. But I had no problems last year, I'd recommend you using the suction cups or whatever mount comes with the heaters so it does not come in direct contact with the acrylic. the key is that water asorbs the heat form the heater. And if that doesn't happen such as directly touching the element to the acrylic that may damage it.