Chlorine demand really low this fall … normal?

[thegizzard]

This is my first season. Most of the year my SWCG was set to 25%-30%. My rpms were set at 1500 for most of 18 hours daily.

I just boosted my pump RPMs to 1800 most of the day and reduced to about 12 hours daily. But now SWCG set at less than 5% has my FC at about 7.5 PPM.

Is this reduced chlorine demand normal in the off-season where temps are about 60F down from high 80s most of the summer?

 

[Bperry]

This is my first season. Most of the year my SWCG was set to 25%-30%. My rpms were set at 1500 for most of 18 hours daily.

I just boosted my pump RPMs to 1800 most of the day and reduced to about 12 hours daily. But now SWCG set at less than 5% has my FC at about 7.5 PPM.

Is this reduced chlorine demand normal in the off-season where temps are about 60F down from high 80s most of the summer?

Yes

 

[jmastron]

Yes, a dramatic usage difference is normal. It's a combination of colder air and (more importantly) water temperatures, and lower sun angles so a lot more shade and less UV even when in the sun for most pools. When I was using liquid chlorine, in the summer I might use a gallon every 2-3 days; in the winter a gallon every month if that to maintain the level, so a 10x spread. SWCG is similar -- I ran mine at 100% for 8-9 hours in the peak summer; 1-2 in the shoulder of winter last year (other than when it stopped generating when the water was below 50 degrees, but needed very little liquid to maintain during that month).

You can probably reduce pump runtime further if your SWCG isn't on a separate timer, or even if it is -- a few hours a day of circulation is probably sufficient now.