How to unfreeze a water trough?

Hmm..I actually had that same problem this morning, but previosuly they were all de-icing just fine. If its just a thin layer of ice, take a bucket to crack the ice, then (if you have water proof gloves) pick up the large ice chunks out of the water. One of the tanks froze over before the heater got put into it and I had to use a sledge hammer to get through it. I would take the heater back to where you got it from, tell them its defective and exchange it for another. If you still have problems go for another brand.