Chlorine color match way off after using Home Depot liquid chlorine.

[Calguy]

I have 2 test kits, a simple Home Depot one with color match and the good TFP one with the powder/drop test for chlorine.

Before I did a SLAM recently with HD liquid chlorine, all the tests would match, HD CL/PH daily test, TFP CL/PH test, and TFP drop test all matched really well.

No though the CL/PH color test is way off, basically it is reading bright/strong yellow no matter what the chlorine level. this week I did the powder/drop test and got readings from 1.5 to 6 ppm, at the same time the color tests would show the same thing the whole time.

This morning for example

CL powder/drop test was 1.5ppm
HD and TFP color match test showed over 5ppm and super bright yellow.

here is the rest of the chemistry

Total CL 0.1
PH 7.4
Total Alk 80
cal hard 210
CYA 60

TDS 1200

I don't mind using the powder/drop test but it would be good to know what may have changed.
Thanks for any help.

 

[bsteveson1]

I have 2 test kits, a simple Home Depot one with color match and the good TFP one with the powder/drop test for chlorine.

Before I did a SLAM recently with HD liquid chlorine, all the tests would match, HD CL/PH daily test, TFP CL/PH test, and TFP drop test all matched really well.

No though the CL/PH color test is way off, basically it is reading bright/strong yellow no matter what the chlorine level. this week I did the powder/drop test and got readings from 1.5 to 6 ppm, at the same time the color tests would show the same thing the whole time.

This morning for example

CL powder/drop test was 1.5ppm
HD and TFP color match test showed over 5ppm and super bright yellow.

here is the rest of the chemistry

Total CL 0.1
PH 7.4
Total Alk 80
cal hard 210
CYA 60

TDS 1200

I don't mind using the powder/drop test but it would be good to know what may have changed.
Thanks for any help.

Same issue. The yellow always appears brighter than the highest color on the kit even when the drop test is lower.

 

[Texas Splash]

Let's be sure the testing is consistent:
10 ml water sample with ONE generous scoop of powder. Add drops and mix until clear, then divide answer in half. Example: 8 drops equals an FC of 4.

If so, and the if the reagents are fairly new this season, then I would always go with the FAS-DPD. Remember the drops (yellow) is showing you both FC and CC (total chlorine), so that could account for some of your concerns. The FAS-DPD is very accurate in separating the two.

 

[Calguy]

Correct, I am following the instructions as you stated and also using my magnetic mixer which makes it so easy.

 

[Calguy]

Let's be sure the testing is consistent:
10 ml water sample with ONE generous scoop of powder. Add drops and mix until clear, then divide answer in half. Example: 8 drops equals an FC of 4.

If so, and the if the reagents are fairly new this season, then I would always go with the FAS-DPD. Remember the drops (yellow) is showing you both FC and CC (total chlorine), so that could account for some of your concerns. The FAS-DPD is very accurate in separating the two.

What brand/type of chlorine are you using?

 

[Calguy]

Let's be sure the testing is consistent:
10 ml water sample with ONE generous scoop of powder. Add drops and mix until clear, then divide answer in half. Example: 8 drops equals an FC of 4.

If so, and the if the reagents are fairly new this season, then I would always go with the FAS-DPD. Remember the drops (yellow) is showing you both FC and CC (total chlorine), so that could account for some of your concerns. The FAS-DPD is very accurate in separating the two.

That's what I am doing with a new tf-100 test kit. The HD test kit is a year old but has been stored well and matches the TFP OTO.

my family is dropping our pool service this month to do it TFP style and they couldn't even measure right with OTO.

I will just order the XL size FAS/DPD Reagent and do that. Thanks.