Pool Math CSI vs Taylor Watergram Wheel

[Jmg_moocows]

I'm 3 months into pool ownership. After researching and finding this site I gained confidence to take care of my own pool. I realized no one else is going to be more invested than me so why pay someone else... so thanks for all the great information!

My #'s are as follows:
FC - 7.8
CC - 0
pH - 7.4 (* been adding MA to bring down alkalinity)
TA - 120 (was at 150 4 days ago, so adding MA every time pH increases through aeration (running. waterfall)
CH - 390
CYA - 58
TEMP - 84 deg
CSI - 0.06

My question is when I use the Taylor Watergram wheel I get a saturation index of 0.25 but the Pool Math CSI is 0.06. Why is there a difference? Are these not the same metrics? Am I reading the Watergram incorrectly?

 

[JoyfulNoise]

Watergram calculates LSI. You also need to correct the TA for CYA with the watergram.

Best to stick with CSI if you intend to follow the TFP method.

 

[Jmg_moocows]

Thanks. Sorry, saw some other posts related to this question after I posted. I will rely on pool math going forward and not worry about Watergram wheel.

Before taking over and doing my own measurements the pH was always hovering around 8.0 and alkalinity was high...I started noticing a Calcium deposit line on some of the waterline tiles. I'm thinking it could be caused by the positive CSI value and I'm hoping to stop further issues.

Am I on the right track?

 

[JoyfulNoise]

Thanks. Sorry, saw some other posts related to this question after I posted. I will rely on pool math going forward and not worry about Watergram wheel.

Before taking over and doing my own measurements the pH was always hovering around 8.0 and alkalinity was high...I started noticing a Calcium deposit line on some of the waterline tiles. I'm thinking it could be caused by the positive CSI value and I'm hoping to stop further issues.

Am I on the right track?

Yes. High pH + high TA is a recipe for calcium scale.