Hi all...
Sorry for the late follow up.
Seems the prestone driveway heat worked fine.
My initial concerns about the high cholroine demand came from me not considered all the variables.
In the summer, following my resurface job, I was running my filter 24/7 with Trichlor pucks in my skimmer. It helped with the acid demand and got my CYA into the pool. Everything was fine.
A few months ago, when the pool company redrained to fix my steps, I was only running my filter 8 hours a day, so I put the pucks in a feeder.
So, I had the following going on:
Less Chlorine going in, because much lower water flow.
Less CYA being introduced because of above.
Much more rain, a lot more organics (debris... Worms)... getting into pool and staying there longer.
I largely ignored these factors, and considered that it was colder (so there would be less demand on chlorine from algea growth), plus shorter days = less UV = less chlorine demand.
Also, in the past, I just let the pool go to swamp in the winter, and never paid any attention to the chemistry.
Now, I have everything dialed in, and am starting to get a feel for the different pulse that the pool has in the winter, and everything is fine.
Prestone driveway heat got my CH from about 20 up to a nice happy 230ish. No ill effects. Only issues were my expectations needed to be adjusted for a few other variables that I didn't consider.