CSI - Pool Math or Taylor nomogram?

sktn77a

Gold Supporter
May 16, 2010
1,421
Chapel Hill, NC
I've been using the Taylor wheel nomogram that comes with their professional FAS-DPD kit for calculating CSI, and using this to keep it between -0.3 and +0.3. Just by chance, I thought I would try the Pool Math spreadsheet, expecting the same results. Imagine my surprise at seeing some pretty significant differences.

The Talyor wheel uses CH, TA, pH and temperature (no CYA).
Pool math uses CH, TA, pH and CYA (no temperature).

Which do the experts consider the better measure?
 

bdavis466

TFP Expert
Platinum Supporter
Aug 4, 2014
5,058
San Clemente, CA
Pool Math uses temperature...why do you say it doesn't?

Pool Math uses total alkalinity and provides several adjustments (bicarbonate alkalinity and cyanurate alkalinity) that make the CSI much more accurate than the spinning Taylor wheel of death. CSI is determined from pH, TA, CH, CYA, water temp, borates and salt level...all of which Pool Math takes in to account and logarithmicly corrects.

Taylor's wheel doesn't truly determine CSI the way Pool Math does, its almost a hybrid of CSI and LSI which is close enough for most pool owners but not the TFP clear water elitists.

The wheel will however work much better than Pool Math as a Frisbee....or a drink coaster.....or a pirate eye patch🏴‍☠️
 
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sktn77a

Gold Supporter
May 16, 2010
1,421
Chapel Hill, NC
Ah, my mistake, it does indeed use temperature. So PoolMath take into account more variables that the Taylor wheel. I guess that has to make it more accurate.

I've been using the Taylor wheel for 2 years, since we got our pool renovated. Will use only the PoolMath spreadsheet from now on!
 

bdavis466

TFP Expert
Platinum Supporter
Aug 4, 2014
5,058
San Clemente, CA
Ah, my mistake, it does indeed use temperature. So PoolMath take into account more variables that the Taylor wheel. I guess that has to make it more accurate.

I've been using the Taylor wheel for 2 years, since we got our pool renovated. Will use only the PoolMath spreadsheet from now on!
Your pool and its occupants will thank you for it!

Please don't forget to post a picture of your Halloween costume

 

JamesW

TFP Expert
Mar 2, 2011
16,592
When using the Taylor wheel, you have to use adjusted alkalinity. The Taylor book explains how to calculate the adjusted alkalinity.

When using the Watergram, you have to use "Adjusted Alkalinity".

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.

 

sktn77a

Gold Supporter
May 16, 2010
1,421
Chapel Hill, NC
Ah, found it. Buried in the middle of the book in an unassuming paragraph!

Might as well still use the PoolMath calculator of I'm going to have to use "off-wheel" calculations!