I live in Greenville, SC. Pool is in my sig line. This is our first year for needing to worry about winter, dont ask about last year!
Winter temps do go below freezing at night but tend to warm quickly during the day. We have several pools in our neighborhood and its about 50% who close and cover vs. keep the pool open year round. Neither one can really give me a good reason to do one or the other. One who covers has a 2yr old who likes to explore the pool area so that was a no brainer.
We dont need to worry about kids or pets, the pool is away from the house in a locked fence. We have a LOT of trees along the property. 100ft tall white oaks, cedar, pine, etc. I am already cleaning leave out of the pool every other day.
Option 1 - keep pool open all winter and just deal with leaves until they are done.
Option 2 - buy a safety cover (wife doesnt like the basic covers), either mesh or solid.
If I go Option 2 I was told to wait until the water is down to 60 to control algae issues. By that time the leaves will be done which was one of the reasons I wanted the cover. Water is still in the upper 70's right now.
I did the math and paying for the power and small chem usage over the winter is much cheaper vs. the safety cover (quoted around $2K for a solid or a new fine mesh). I could keep it open every year for a decade and still be ahead money wise.
I think my Ecostar pump and Haywood SWG have a freeze protection built in where they will kick on if it gets below freezing. If not I can easily switch run cycle to run during the night vs. day or just keep it running if weather looks cold. I assume I just need to keep the speed high enough to make the water circulate.
Anything else I am missing? Again, the main reason for the cover was leaves! Prior to the pool being installed it was a leafy mess in the yard so I know how much will be heading towards my pool shortly.