Confessions of a cheapskate:
Living in Texas, I have found that below about 65F water temp, I don't need chlorine. Water temp seems to stablize between 50-55F usually in the winter if that makes any difference.
OMG NO!
So basically once I hit that number, I let the chlorinator run dry (so to speak) of the tri-chlor tabs, and pretty much the rest of the time just get leaves out of the pool until the water temp starts to go back up. I also cut the filter run time back to two 3 hours sessions a day from two 4 hour sessions. So pretty much from Nov. through March/April (depending on the weather and water temp) NOTHING gets added (unless I need water, but don't recall having to add water). Maybe a backflush (DE filter) maybe even two if pressure increases, but usually no more than one during the winter.
In the spring when the temp starts going up, I usually shock it, and then after a few hours take a water sample to my LPS (always the same one) for a reading. So far every spring the CYA reading is 20-25 lower than in the fall (usually a reading 1 month before the water temp reacheas my cutoff).
This spring it might be interesting to see if there is any differance since I did sprinkle a bunch of Cal-Hypo (shock) in letting it settle on some organic stains (didn't seem to make a differance to the stains) and see if that effected the CYA lowering at all.
Anyway just thought it worth a mention.
No covers, no nuttin except my automatic pool cleaner, my leaf rake and me all winter. 30K plaster IG