I haven't seen those. If it specifically says that it's okay to be used with aquaria, then it's okay in my book. I just take exception to reptile heating pads. Those things get up to 100* easy. I know, I have several snakesTKOS said:I don't know how well they work but they do sell under plant heating pads that are water resistant. They may have the same issues as the reptile pads Roan indicates but are meant to get splashed with water. Unfortunatly they also only add a few degrees so would be opperating constantly.

Doesn't mean I advocate using them as a heater, just that they are safe to use as a heater

Couldn't have said it better.In a smaller tank spending more on a heater can sometimes be the best idea as they are not tolerant of large swings. A 50 gallon tank can survive much longer if a heater gets stuck on than a 2 gallon.
Roan