CYA and Chlorine

[mynewpool]

I have seen a few times on the website where it says FC should be 7.5% of cya. Per the target level on the CYA chart in pool school, it shows at 40 CYA to have a target of 5, which is around 12.5%. Have I read into this wrong or what is the amount of FC with a given CYA?

Thanks.

 

[Bama Rambler]

If you look at the chart you'll see that for a CYA of 40 the minimum FC level is 3 which is 7.5% of the CYA level. Now the target is at a level so that given normal 2 ppm loss during the day will still leave you with a FC level of 3. If you tried to maintain a level of 3 there would be times when it'd get away from you and drop below that and leave you open to algae or worse.

 

[mynewpool]

If you look at the chart you'll see that for a CYA of 40 the minimum FC level is 3 which is 7.5% of the CYA level. Now the target is at a level so that given normal 2 ppm loss during the day will still leave you with a FC level of 3. If you tried to maintain a level of 3 there would be times when it'd get away from you and drop below that and leave you open to algae or worse.

Got you thanks for explaning. So the min is incorporating the FC loss during the day?

 

[Bama Rambler]

The min is what you never want to go below. The target incorporates the normal loss during the day so you'll always be at or above the min.