The 50 watt heater I'm using is (unfortunately) the one labeled FAILED on Aart's instruction post
wish I noticed the post before I bought it! Oh well, hoping mine will hold out for the season at least, we don't get overly cold here (down to the 20s at night) and so far the heater is doing it's job, but I am keeping an eye on it. An inch of snow everywhere this morning, but the girls still had a working water nipple.
Are you using a thermocudbe too? That would help with the failure rate, that and keeping the water topped up.
The reason I went with the pipe heating cable is because I already had it and there was no need to buy a thermocube.
The wire has a built in thermostat, turns on off like a thermocube and it's designed to keep pipes from freezing.
The bucket is like a big pipe, but it also has a lot more wire wrapped around it.
If your weather only goes down to the 20s, you shouldn't have an issues keeping it from freezing, as long as something doesn't break.
It's 23F right now with no frozen nipples and I'm only using 18watts, your 50 watts should be fine.
aart gets colder temps than you and it works for him.
I'll know by the end of next months if mine is gonna work. The end of January, Feb are our coldest months.
aart method is proven to work for the low temps he gets. My temps are 2.5 times colder some nights and I live in the warmest winter province in Canada, god help those who live in colder provinces.
If mine starts failing, I'm gonna add aarts method to it, dual heaters.