Does seem every winter a large number of people have heater issues., with being stuck on being the worst case.
I have gone over a fairly large number of back posts, here and other sites, and have found most all reported deaths were in tanks where the watts per gallon were 5 watts to a gallon, or more.
Not everyone of the boil outs, TC`s 90, with a 200 as an example, but most..
With our present cold snap, I finally needed a heater myself.
Off to walmart and got the smallest heater my store had.
Cheap-o, tetra 50 watt for my 55g.
It did take a few days of this being on almost all the time, to bring the tanks temp. up to the 78 range.
I have pretty decent circulation, a pair of penguin350.
So what?
What I am thinking is low watts per gallon, coupled with good circulation would equal no worries about boil out.
Even if the heater were to stick on, the worst this little heater could do is mid 80s` for my tank.