I recently changed my FBT's setup to mainly water. I think that they are getting a tad cold from a window draft. I went to get a water heater and the store was out. Then I got to thinking...I have a small 4 watt (1-5 gallon) under tank heater I'm not using. Do you suppose it would be ok to tape it to the side so it heats the water a bit? Or would it shatter the glass (5gal glass tank)? I know with my crabs no water can hit the area of glass its on because it will shatter. But the water is cold and the pad is cold so I just was curious. Or should I stick it so it warms the air instead?