I want to understand if I can have higher FC levels in the presence of CYA than without CYA, and still have no negative impact on the human body (eyes/skin). I know how CYA impacts the desinfection effect but I find no information on how to calculate the ”max” FC level.
Maximum FC level
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drsipe
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Maximum safe chlorine level for equipment and swimming is SLAM level
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HOCl (hypochlorous acid) is what sanitizes the pool. This chart gives you the HOCl concentration at various FC and CYA levels.
0 CYA and .2 FC is about .1 HOCl.
30 CYA and 10 FC is about .1 HOCl.
Hopefully that helps you understand and use this chart. The horizontal lines are the levels of HOCl that kills Bacteria and Algae.
Source:
Pool Water Chemistry
This thread presents my findings so far on pool water chemistry including the following: More Accurate Calcite Saturation Index (CSI) to replace Langelier Saturation Index (LSI) Calculation of ppm HOCl (disinfecting chlorine) at various levels of Total Free Chlorine (FC) and Cyanuric Acid (CYA)...
www.troublefreepool.com
Do you mean (with values from the chart) that at CYA 20 ppm the FC level could be as high as 10 ppm and you could still swim in the pool? What is the meaning of the target range column values?
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For maximum FC to swim for your CYA, use 40% (basically slam level FC). So if your CYA is 20, 40% of 20 is 8ppm. So swim up to 8ppm if your CYA is 20.
If you mean from the FC/CYA tool? You should keep your FC within the target range for your CYA.
My question was not regarding what minimum levels are required for sanitation, but what are the maximum levels that are allowed and the water still being ”nice” for the human body.HOCl (hypochlorous acid) is what sanitizes the pool. This chart gives you the HOCl concentration at various FC and CYA levels.
0 CYA and .2 FC is about .1 HOCl.
30 CYA and 10 FC is about .1 HOCl.
Hopefully that helps you understand and use this chart. The horizontal lines are the levels of HOCl that kills Bacteria and Algae.
Source:
Pool Water Chemistry
This thread presents my findings so far on pool water chemistry including the following: More Accurate Calcite Saturation Index (CSI) to replace Langelier Saturation Index (LSI) Calculation of ppm HOCl (disinfecting chlorine) at various levels of Total Free Chlorine (FC) and Cyanuric Acid (CYA)...
Great thanks for this. Just to be clear, at CYA 20 ppm the FC level should be minimum 2 ppm and max 8 ppm, but try to keep it between 3 and 5 ppm ?
What is the source of the ”40% rule” ?
I did explore this before making my post, but I did not find the answer there - however there was an article that had a promising title, but that article did not ”deliver”
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Yes.
A lot of testing and experimentation over a long period of time.
Chlorine/CYA Chart
EDIT: You will find a simplified and standardized version of this chart at Pool School, Chlorine / CYA Chart. Chlorine/CYA Chart by Chemgeek FC = Free Chlorine in parts-per-million (ppm) CYA = Cyanuric Acid in parts-per-million (ppm) CYA ........... Min FC3 ..... Target FC ...... Yel/Mstrd...
www.troublefreepool.com
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There’s nothing magical about the 40% FC/CYA ratio that TFP uses for its SLAM criteria. It’s a balance between having enough chlorine in the water to really overwhelm the algae versus using a level that safe for people and equipment. The higher the FC level, the higher the intrinsic chlorine loss rate (loss not associated to disinfection). So, at some point it makes no sense to add higher levels of FC as you’re only wasting it. That “line in the sand” for TFP is 40%.
ThanksYes.
A lot of testing and experimentation over a long period of time.
Chlorine/CYA Chart
EDIT: You will find a simplified and standardized version of this chart at Pool School, Chlorine / CYA Chart. Chlorine/CYA Chart by Chemgeek FC = Free Chlorine in parts-per-million (ppm) CYA = Cyanuric Acid in parts-per-million (ppm) CYA ........... Min FC3 ..... Target FC ...... Yel/Mstrd...
JupiterFL
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Also, and Poolstored corrrect me if I am wrong, but the HOCL at SLAM level is less than any of the “authorities” reccomended FC levels with no CYA.
Is it correct, with some scientific backing, to assume that without any CYA most of the FC is HOCl and then around 3 ppm is the ”max” allowed level. With CYA you could say that the ”max” FC level is the FC level that gives a HOCl level of around 3 ppm? I.e. It is basically the HOCl level that determines both the max and the min limits, and the required FC level needs to be choosen so that the target HOCl gets fulfilled?