what to do if colors on the CL/pH test are inbetween?

crackers8199

Well-known member
Jun 5, 2014
113
Lake Elsinore, CA
just did my daily morning test with the K1000, and for the first time i noticed that the shade of red on the pH is obviously neither 7.5 nor 7.8, it's somewhere in between. is it valid to guess 7.6 or 7.7, or is it best practice to log it as one or the other (and if so, which one)?
 

Msch99

Gold Supporter
Bronze Supporter
Jun 11, 2018
900
Verona, MO
Either one, maybe stay consistent with what you do. All are within range so not a biggie. .1 or .2 shouldn’t make much difference in CSI which I know little about.
 

crackers8199

Well-known member
Jun 5, 2014
113
Lake Elsinore, CA
Either one, maybe stay consistent with what you do. All are within range so not a biggie. .1 or .2 shouldn’t make much difference in CSI which I know little about.
my CSI should stay below 0.3 with my other params until i hit 7.8, then it starts getting into the outer range. at 7.5 i'm at 0.08, at 7.7 it's 0.27. i have been adding acid once i hit 7.8 to try as hard as possible to reduce the possibility of scale, since my CH is so high (1250!)
 

Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
6,164
Central California
I always guesstimate the in-between. Though my tester's increments are 2 points apart, so 7.2, 7.4, 7.6 etc. If it's not quite orange enough, or red enough, I'll record 7.5, etc. I'm fanatical about my CSI, so I like to enter as accurate a pH number as possible. Keep in mind though, that testing procedures, and the tests themselves, can have quite a margin of error, so you can't get too crazy. I think a lot of the Taylor tests have a 10% margin, so there's that.

Consistency is the key to useful test results. I recently had a little bout of algae on my pool walls. I had slipped up and my FC dropped to 2.5. So now I know where my pool's threshold is (at least for that time of year). So it doesn't really matter if the FC was actually 2.5, it only matters that I test consistently, so if I again get a result of 2.5, then I'll know I'm in for some trouble. Additionally, every pool is different, so the "algae threshold" of 2.5 in my pool might be 1.5, or 3.5 in someone else's. So the test results, however accurate, are always only a guide for what works in your pool. It's consistent test procedures that make the numbers reliable in your pool. How your pool reacts to a given chem level. How that compares to others' results, including TFP guidelines, is less important...