Pool Math App question

Pietecasius

New member
Aug 6, 2019
4
Harrisonburg, VA
How do i change the Free Chlorine range in the pool math app? It is set for 1-3ppm, and based on a Salt pool with a target CYA of 70, my range should be 3-5 (according to TFP CYA/FC chart) I can’t figure out how to change the range in the app. Thanks in advance for any help!
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
26,972
Laughlin, NV
Welcome to the forum!
Be sure you have the CYA value entered and saved. Along with selecting a SWCG in Setting up Your Pool. The FC range should then adjust. The 1-3 ppm you are seeing is because the app thinks you have 0 CYA.
I suggest you read ABC's of Pool Water Chemistry.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
16,251
Northern NJ
Welcome to TFP.

Did you set the type of sanitizer to SWG in PM?

Log your CYA of 70 and it should tell you your FC range is 3 -10.
 

Leebo

Admin
TFP Expert
LifeTime Supporter
Jul 21, 2011
9,538
Eastern Ohio
Looking at your logs shows you currently have it entered as a CYA level of 2, likely a typo somewhere. Alter that and your target will be updated.
 

Pietecasius

New member
Aug 6, 2019
4
Harrisonburg, VA
Thanks Everyone. I have read pool school. Im fairly well versed on pool care, just new to the app, and SWCG. I didnt realize the app was auto setting the FC range off of the actual CYA test. CYA reading of 2 is correct. I am in the process of raising the CYA on a new pool fill. Sounds like FC range will solve itself as CYA comes up. Thanks for the help!!
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
26,972
Laughlin, NV
A test result of CYA of 2 is not possible.

Is that water chemistry test device you show in your signature your own?
 

Pietecasius

New member
Aug 6, 2019
4
Harrisonburg, VA
Mknauss, why is a CYA result of 2 not possible? As the chemical is added to the water feom 0 ppm it will be 2 ppm at some point. If you are referring to the resolution of a particular test method, I own and use a Pool Lab 1.0 photometer to test my water. Pool store test results matched my results exactly on all parameters from split sample. I was in the water bottling industry for 15 years and I am not a fan of certain reagent and titration tests when there are better more accurate methods. I used photometers extensively at work, and have found the Pool Lab to be quite accurate and repeatable.
 

Leebo

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Jul 21, 2011
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Eastern Ohio
If I may ask, what chemicals have you added to the water? Do you use pucks, or powdered shock?? Even if (and it’s a big if) the result was possible, is there a reason you’re attempting to maintain such a low CYA level?
 

wogster

In The Industry
Apr 30, 2018
148
Toronto, Ontario, Canada
Mknauss, why is a CYA result of 2 not possible? As the chemical is added to the water feom 0 ppm it will be 2 ppm at some point. If you are referring to the resolution of a particular test method, I own and use a Pool Lab 1.0 photometer to test my water. Pool store test results matched my results exactly on all parameters from split sample. I was in the water bottling industry for 15 years and I am not a fan of certain reagent and titration tests when there are better more accurate methods. I used photometers extensively at work, and have found the Pool Lab to be quite accurate and repeatable.
So a question, how are you keeping the meter calibrated? Matching the results of a pool store, is not an indication of accuracy (lots of people around here would seriously doubt your results if they match a pool store).

So while a CYA number with an accuracy of +/- 1 is more accurate then a CYA number of +/- 10; Being that accurate is not always helpful. I have not seen the code for the Pool Math App, FC is a range of known values; So rather then trying to compute the range, you use a lookup table, that's how I would do it....
 

Pietecasius

New member
Aug 6, 2019
4
Harrisonburg, VA
If I may ask, what chemicals have you added to the water? Do you use pucks, or powdered shock?? Even if (and it’s a big if) the result was possible, is there a reason you’re attempting to maintain such a low CYA level?
Not trying to maintain a low CYA level, that happened to be the level the day after the pool was filled and the builder threw in three bags of shock.
 

Leebo

Admin
TFP Expert
LifeTime Supporter
Jul 21, 2011
9,538
Eastern Ohio
If I may make a comment,
You’ve added several pounds of CYA according to your logs. Now add that your builder has added CYA also. It’s some serious red flags that make me worry about your actual level. Your current result just doesn’t jive.

Not wishing to bash your test, but I’d greatly suggest you move very slow in this one. Part of my wonders if the cold water maybe altering your readings.
 

setsailsoon

Gold Supporter
LifeTime Supporter
TFP Guide
Oct 25, 2015
2,569
Stuart/FL
P,

Lee's making a good point. Should be about 21 ppm CYA. Decimal error? As Lee pointed out you may want to double-check before you add anymore CYA just to avoid going too high accidentally.

Looking at your signature. Looks like a nice pool with some great equipment. Congrats!

Chris