Chicken water freezing

We have a HD bucket for a waterer that has pipes coming out with watering cups at the end of two pipes.   (Link showing cups)  They are awesome when not frozen!

http://www.strombergschickens.com/product/drinker-cups-package-of-five-for-the-automatic-drinker-cup-system/automatic-drinker-cup-system

We have heat tape wrapped around the bottom of the bucket and the pipes but the stupid watering cups freeze.  I have been and will be apparently going out every morning and dumping a 2 quart bucket of hot water on the cups to thaw them out. 

My husband spent Monday making a small Christmas tree light bulb like for the houses into a can heater and then put it under the watering cup and put mortar on top to cup the cup and keep it from freezing.  It didn't work. 

I had put a normal waterer inside the coop and it froze.  I saw somewhere to take a cookie tin with a 40 watt light bulb inside and have it under the waterer so that is what I'll be trying tomorrow when I'm off.  The cups will thaw out during the day and meanwhile they will have water inside.