PM FC recommendations not lining up with Pool School

[grunky_peep]

I'm looking at this FC/CYA chart here:

CYA Chlorine Relationship - Further Reading

www.troublefreepool.com

It says for my CYA of 80, I need a minimum of 6 FC, with an idea range of 9 to 11.
However, in the Pool Math iOS app, it shows the recommended range is 4 to 11 FC.

I'm making a guess that the chart is correct, and I should use the 6 minimum, but ideally should be in the 9 to 11 range, rather than 4 to 11?

 

[PoolStored]

ideally should be in the 9 to 11 range

^This. Join team #runhot. being 9-11 protects from high demand days. In Ohio (less sun than you) I can use up to 5.5FC. 10-5.5=4.5, still above minimum.

 

[grunky_peep]

^This. Join team #runhot. being 9-11 protects from high demand days. In Ohio (less sun than you) I can use up to 5.5FC. 10-5.5=4.5, still above minimum.

That's a great point. Our summers are TOASTY and the sun absolutely nukes our pool. 9-11 it is, but still odd that the app would suggest 4 to 11, especially when pH has a recommended range, then a separate ideal range. I would have thought FC would be the same. Show 6-11 recommended, and 9-11 idea. Or something.

I've been running 4-6 normally, and I've been wondering why the water has been looking slightly on the cloudy side, and gets cloudy super quickly (less than an hour) when there's a handful of people in the pool and clean filter carts. Then I found that FC/CYA chart and it all makes sense.

 

[PoolStored]

I've been running 4-6 normally, and I've been wondering why the water has been looking slightly on the cloudy side, and gets cloudy super quickly (less than an hour) when there's a handful of people in the pool and clean filter carts. Then I found that FC/CYA chart and it all makes sense.

I run my SWCG at 35% in May/June. That works with cover and no swimmers. If I have swimmers, I turn my SWCG up to 50% from the time we pull the cover until I go to bed and then turn it back to 35%. Raising it for the day covers the FC demand from the swimmers. If you have super high demand, you can even test and add liquid chlorine during the day to keep your FC up!

 

[Bperry]

I'm looking at this FC/CYA chart here:

CYA Chlorine Relationship - Further Reading

www.troublefreepool.com

It says for my CYA of 80, I need a minimum of 6 FC, with an idea range of 9 to 11.
However, in the Pool Math iOS app, it shows the recommended range is 4 to 11 FC.

I'm making a guess that the chart is correct, and I should use the 6 minimum, but ideally should be in the 9 to 11 range, rather than 4 to 11?

The app has the option to know you’re using a SWG and TFP has some kind of feedback that you can get away with slightly lower FC levels when doing that. The chart is just the straight info.