pH differences

[Lampasas1]

I had a sw pool installed at the end of last year. I have never been able to consistently keep pH below 8 using the tf pro test kit. I check pH and chlorine every 3-4 days and pH is always above 8 on the comparator block. I will add muriatic acid, usually a cup, and can get pH back to around 7.5. But after a few days pH will drift back up over 8 (guesstimate as the comparator values jump from 7.8 to 8.2). Occasionally it jumps over 8.2. After reading many posts, it seems like this is a constant battle that I will have to endure. My TA is 50 and I don’t want it to get any lower with continual ma additions.

This morning, I found the cheap pH comparator kit the pool installer left me and decided to use it and see how it compares to the tf pro. The cheap comparator uses 4 drops of phenol red vs tf pro using 5 drops pH indicator

I measured between 7.6-7.8 with cheap kit vs 8 or above with the tf pro. See pics below. Why is there a discrepancy and which value should I use?

 

[mknauss]

Use 4 drops of reagent.
It is the hue, not intensity, of the color that matters. To be 8 or over, the hue would have purple in it. Yours does not.

 

[Lampasas1]

Use 4 drops of reagent.
It is the hue, not intensity, of the color that matters. To be 8 or over, the hue would have purple in it. Yours does not.

I forgot to mention that I actually started with 4 drops and I felt like it was still above 7.8. Then added an additional drop (as per test kit instructions) and took the picture. I will keep trying.

Regarding TA. Should I consider adding baking soda to raise it a bit?

 

[Donldson]

Chlorine affects the pH reading. The Taylor reagent has enough chlorine buffer to register correctly up to 10 ppm FC, but cheaper ones usually start showing off above 5 ppm with some even as low as 3 ppm.

So that could be a factor.

 

[Lampasas1]

Also, I am running low and need to reorder more pH indicator. Expiration is 9/24 on my current reagent. That shouldn’t effect results, right?

 

[mknauss]

Your reagent is fine.

Add 20 ppm TA worth of baking soda when your TA reads 40 ppm.

 

[Bperry]

I had a sw pool installed at the end of last year. I have never been able to consistently keep pH below 8 using the tf pro test kit. I check pH and chlorine every 3-4 days and pH is always above 8 on the comparator block. I will add muriatic acid, usually a cup, and can get pH back to around 7.5. But after a few days pH will drift back up over 8 (guesstimate as the comparator values jump from 7.8 to 8.2). Occasionally it jumps over 8.2. After reading many posts, it seems like this is a constant battle that I will have to endure. My TA is 50 and I don’t want it to get any lower with continual ma additions.

This morning, I found the cheap pH comparator kit the pool installer left me and decided to use it and see how it compares to the tf pro. The cheap comparator uses 4 drops of phenol red vs tf pro using 5 drops pH indicator

I measured between 7.6-7.8 with cheap kit vs 8 or above with the tf pro. See pics below. Why is there a discrepancy and which value should I use?View attachment 603123View attachment 603130

The pH in this TF-100 comparator picture is well below 8.0

 

[pjt]

I am running low and need to reorder more pH indicator.

Make sure you get the correct one. R-0004 and R-0014 are both phenol red, but designed for different color comparison blocks.

 

[Redsurprise]

like you My pool was new in February and my pH is always at 8 or higher . I can put recommended acid in according to pool math. Lower pH to 7.5, and then next day my pH is back to 8. I have yet to find a solution to this . I use the TF pro kit also . My TA is 70. I tried lowering it to 60 and it didn’t make a difference. Always 8 (Barbie hot pink) on the comparator block. I hope you can find a fix Lampassas1.

 

[mknauss]

Always 8 (Barbie hot pink)

It is the hue, not intensity, of the color that matters. To be 8 or over, the hue would have purple in it. Yours does not.

An 8 will have a purple hue.

 

[Redsurprise]

An 8 will have a purple hue.

So how do we know what our true pH is then? What does Barbie hot pink equal if it we are going off of hue? I try to verify against my calibrated pH Pen and it says it is 8.2.

 

[mknauss]

Yellow is below 7. Orange is low 7's. Reds are mid/upper 7's, purple are 8+

 

[kenlip]

Using Lightroom, I cloned a small area from each level indicator over the sample.