High Chlorine Levels w/ low output % on SWG


Well-known member
Jun 18, 2007
Spring, Texas
On initial start up back in September, I had my SWG set at 60% output and was running about 5ppm at that setting. When the weather started cooling down, I noticed that the chlorine levels shot up dramatically...to about 10ppm. I had about .5 in FC. I Super Chlorinated the pool (100% SWG for 24 hours) then backed the SWG down to 35% output. Leveles are still varying between 8 and 10ppm. Any advice? Should I drop output even lower?



Chlorine demand can drop dramatically when the water temp drops. If you have been maintaining an 8-10 ppm fc for about 2 weeks or longer since dropping your output to 35% then you can either reduce your pump run time (I drop down to 6 hours a day in winter compared to 8-9 during the summer) or lower your output some more, perhaps to about 25% and then give it a couple of weeks to stabilize. You should still check the FC on a regular basis and if it starts going too low bump up either your output or run time.


LifeTime Supporter
Jul 24, 2007
Suwanee, GA
I had been maintaining about 3ppm at about 15% output on my SWG in late Sept and Oct, but recently I saw it rise to about 7-8ppm. I was lax about changing the percentage since I knew the SWG quits operating when the water hits 55 (so I thought), the pool has been hovering in the low 50s. A few nights ago, seeing it was still high, I changed the output to about 10% and I've yet to test it again. I looked in the manual (just moments ago) and see that the magic number is 51 degrees and not 55.


In The Industry
Feb 4, 2008
It may also help to decrease the amount of time that your pump runs. Most SWG's run whenever the pump is circulating water. Less run-time = less chlorine produced. Colder water doesn't need as much circulation either.