FC jumped this week!

[frankmcs]

I’m a new pool owner (pool is 5 months old). i do all my own testing and my FC has always been in the 7s every week! This week it jumped to 11. Any ideas what caused this? All my other numbers are good! I’m in AZ and the water has definitely dropped in temps! Anything I should worry about?

 

[Bperry]

I’m a new pool owner (pool is 5 months old). i do all my own testing and my FC has always been in the 7s every week! This week it jumped to 11. Any ideas what caused this? All my other numbers are good! I’m in AZ and the water has definitely dropped in temps! Anything I should worry about?

Assuming you didn’t increase your SWCG output then it’s likely the cooler temperatures requiring less chlorine demand. Totally normal.

 

[Mdragger88]

What @Bperry said
Time to adjust the percentage down a lil bit for winter
When/if water temps fall below 60 degrees you will need to manually chlorinate with liquid chlorine as the cell will no longer produce.

 

[Newdude]

+3. Think of a bell curve for daily loss / FC demand. This part of the season it falls off a cliff and you overproduce. Up north we had it a month + ago.

In the spring, you will be on the lookout for the daily demand to increase so you can match it. If you miss an adjustment time, you'll be below minimum and on your way to swampville. Regular testing will save you from missing it, or from letting it get out if hand if you don't realize it the first day.

No two seasons are the same but most years was about 5 adjustments whether it was up up down down down, or up up up down down. Maybe add another up and down for the longer seaso.

 

[ajw22]

Lower sun angle hits the pool with less UV which degrades the chlorine less.

We are within a few weeks of minimum sun angle and chlorine loss due to the suns UV. Once we get into January you will find chlorine loss will begin increasing until its peak on June 21.

You need to adjust your SWG to track the change in the suns UV impact on your pool chlorine.

 

[Gary Davis]

I have been experiencing similar longer-lasting FC levels for probably the same reasons!

At what water TEMPERATURE do you decide to close your pool (and can algae grow at that temperature without chlorine)?​

 

[Bperry]

I have been experiencing similar longer-lasting FC levels for probably the same reasons!

At what water TEMPERATURE do you decide to close your pool (and can algae grow at that temperature without chlorine)?​

You are in mid-CA, you don’t need to close the pool. Algae grows at any temperature, just slower.