I didn’t know if I was better off leaving my hot tub run all year, or drain the water and refill it.
I monitor the cost to heat my hot tub. I overlap with the waste water cost averaging my city does. That determines the price of water for the year.
I found it was better to completely drain my hot tub for 4 months and fill it, rather than leave it running at a cooler temp.
Water is more expensive than my electric!