Adjusted alkalinity

Franswois

Member
Jun 19, 2020
5
Dallas, TX
Hi all,

Does anyone know the formula for the “adjusted alkalinity” number Leslie’s lists on their tests?

Is it: alkalinity - (cya/3)?

Thanks! Just switching over to TFP so I don’t have my own test kit yet.
 

Franswois

Member
Jun 19, 2020
5
Dallas, TX
Great, thanks!

I am using the pool math app. I figured I needed to reverse Leslie’s adjusted alkalinity before I input it into poolmath because the pool math app is expecting the unadjusted number.
 

JamesW

TFP Expert
Mar 2, 2011
23,388
The adjusted alkalinity is the TA - (CYA x cf).

Cf is the correction factor, which is based on the pH.

pH........CF
7.0.......0.22
7.1.......0.24
7.2.......0.26
7.3.......0.28
7.4.......0.30
7.5.......0.32
7.6.......0.33
7.7.......0.34
7.8.......0.35
7.9.......0.36

For example, if the pH = 7.6, TA = 90 and CYA = 70, the adjusted alkalinity is 90 - (70 x 0.33) = 67.
 

Donldson

TFP Expert
LifeTime Supporter
Jun 12, 2009
4,669
NW Ohio
First: welcome to TFP!

Don't try doing this using Leslie's or any other pool store testing. They aren't reliable and you could end up running in circles, or worse. You want accurate numbers to go on and that means your own testing.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
36,300
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
I figured I needed to reverse Leslie’s adjusted alkalinity before I input it into poolmath because the pool math app is expecting the unadjusted number.
You need a proper test kit, see Test Kits Compared. I suggest the TF100. A proper test kit is needed to get the accurate water chemistry results needed to follow the TFP protocols.
 
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Franswois

Member
Jun 19, 2020
5
Dallas, TX
Yep, I’m working on getting a test kit so I can do it myself—just using the pool store numbers until I have it in my hands.

Thanks everyone for the help and support.
 
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