Once the temperature drops below 55 degrees at night, the algae in the pool becomes inactive. In addition, there are generally have fewer violent storms during the winter months, so less debris gets into the pool. That means the amount of chlorine needed to keep the pool blue and clear drops way down as well.
The best way to tell is to check the chlorine levels using test strips and/or an OTO test kit. Generally, 1-2 tabs per month will work just fine until the night time temperatures start to rise above 55 degrees again. That’s when the algae starts to wake up and you need to monitor your chlorine levels more closely.
That doesn’t mean you should walk away and leave your pool alone during the winter. Keep up with the maintenance — brush the walls and floor, skim and keep debris from providing food sources for algae once the weather does warm up.
On a side note, right now swimming pool heaters are in use, and the Pool People are getting plenty of calls for service. In one instance, a client called to say the heater started smoking after a few minutes of run time. As it turns out, a mouse found the housing of the heater a great place to nest. Each time the client turned the heater on, the nest caught fire.
We at Pool People recommend that if you have a heater , you should turn it on every month and let it run for about five minutes even during the summer months. Heaters are like a car and not running is bad for them since air can build up in the lines. In addition, by turning on the heater, critters are less likely to be drawn to the warmth and build nest in them.