First winter with pool chem questions

[cantwells]

I am located in Northern California where I may get snow possibly once a year. While I don't plan on using the pool during the winter, I also did not plan to cover it. Is that a mistake? Is there a chemistry that needs to change during the winter months? Also, with the expected El Niño coming, is there anything I should do?

 

[chem geek]

Unless you get a hard freeze over a significant period of time, you can keep your pool open in the winter which means you still keep it circulating with water though can run the pump over a shorter time. If you do expect freezing temperatures, you can run your pump during that time (on low speed) and that will prevent the water freezing in the pipes. You would maintain similar water chemistry in the winter except that your pH target will be a little higher (say, 0.2 units higher) but that usually happens normally as the water gets colder. You should find your chlorine usage dropping significantly with the colder water and lower angle of the sun (and more cloudy days).

You can use the rains from El Niño to refresh (dilute) your water to keep salt levels in check since otherwise they would build up. This assumes you are using chlorinating liquid or bleach. If you are using stabilized chlorine (e.g. Trichlor or Dichlor) then your CYA may be too high or if you are using Cal-Hypo then your CH may be too high. You can use the winter rains to dilute the water and not pay for it from fill water.