I really despise pH testing.

My comparator doesn’t have that yellow test side, and it has smaller ranges. Even then I find that if I use my thumbs or fingers to cover neighboring colors I can focus in better on the hue. Having so many extra colors around in your pictures really confuses my eyes. I think with that test kit I’d use some card stock to cover the yellow side and to limit the view on the pH side to two blocks and slide the cover up or down as necessary to determine where you are. I also find that using a pale beige background helps (conveniently the color of my walls). Maybe reducing visual distraction would help.
 

Spa Owner

In The Industry
Jul 14, 2017
162
Victoria Park, Antipodean
I only read this as I was curious...

With colorimetric comparators there is an easier way to use them...easier being subjective as it depends on eyesight.

TestComp.jpg
I call it the not technique...It works on a not this not that basis. It makes it much easier to work out what it is. I have marked up the photo to show the sequence of elimination. Effectively by eliminating we reduce the choices, and this works better than simply matching what is.

On the other hand we aren't building rockets. So a bit of casualness is okay.

In the sample as presented and subject to computational colour differences the reading appears to sit closer to 7.8 than 8.2 making it between 7.8 and 8.2. This could be anything from 7.85 to 8.15 and I am unsure of the accuracy of the reagent. This would be close enough on pH alone for the purpose.
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
This is pretty much what I do I think.

In my day job, I actually design rockets, and more often than you would think, close enough is good enough :shock:
 

tomfrh

Well-known member
Jan 30, 2018
410
Australia
This is pretty much what I do I think.

In my day job, I actually design rockets, and more often than you would think, close enough is good enough :shock:
I remember listening to the Apollo engineers taking about calculating the burns. At first they said were really nervous and did every burn super precise, but then soon learned there was plenty of margin for error and that they could be looser and that they could easily correct with the next burn.

I think the same is true when reading pH and chucking some acid in the pool.
 

JimMarshall

Gold Supporter
TFP Guide
Jun 5, 2017
1,003
Oil City PA
Just an update here!

Marty, thank you so, so, SO much for the reminder about FC>10 and causing me to question my results and check, double check, and triple check my measurements before making any adjustments. It saved me from accidentally bottoming out my pH and then having to re-adjust upward to keep from discomfort on eyes.

After adding LC and calcium chloride last night , this morning’s test results are as follows:

FC 6
CC 0
pH 7.6
TA 70
CH 275
Temp 85
CSI -.12