PH Difference between K2006 & K1000

[chem geek]

Sometimes the comparator colors in the K-1000 aren't as accurate so first off compare the comparator tubes of the K-1000 vs. the K-2006 to see if they match or are consistent. If not, then that's the main source of the problem. You can also do parallel pH measurements with samples in each tube and compare the color of the samples side-by-side. Remember that you aren't trying to match saturation, but rather hue. This can sometimes be tricky to do. You may find that you can use fewer pH Indicator drops in the K-2006 for a less intense color that is easier to match against the reference colors. The phenol red indicator is the same in both kits except for concentration and that should only affect saturation and not hue.

7.0 will be quite yellow while 7.5 will be more of an orange-red so they should be quite dramatically different. With CYA in the water, even a high FC doesn't affect the pH test until after a minute or so (i.e. that reaction is apparently slow). If you still find a significant difference in hue (after trying more or fewer drops of indicator to try and get the saturation level to be similar), then there may be something wrong with one of the indicator dyes. These are organic dyes and they do degrade over time which is why Taylor recommends replacing them once a year though in practice one can usually go 2 years before replacement. Taylor says that for the phenol red indicator dye "As it degrades, the solution changes from its original red color to a yellow or purple."

[Cookieman]

Color charts on the tubes match up pretty well. Started doing parallel tests, and only once did they come close to matching. The sampling with the k1000 consistently produces a more reddish orange color than the k2006 in my sampling over the last few weeks. Dye looks good - still red and kit is less than 8 months old. While I understand I need to be matching hue, not sure I understand using fewer drops, as I have not had a problem in matching sample color with comparator tube. I did attempt a couple of times adding more drops and it did intensify the hue, but only moved the the "visible match" up one on the scale. To me it made it a bit harder to match the sample to the tube colors. I have not reacted to the low ph yet, but ready to do so if it gets worse. Thanks

[BigDave]

...The phenol red indicator is the same in both kits except for concentration...

My apologies for asking, but, are they the same? The K-1000 comes with R-0014, and the small comparator that reads 6.8-8.2(6.8, 7.2, 7.5, 7.8, 8.2). The K-2006 comes with R-0004, and the large comparator that reads 7.0-8.0(7.0, 7.2, 7.4, 7.6, 7.8, 8.0). I thought (don't know why) that the R-0004 was stabilized for higher chlorine.

[Cookieman]

Yes the scales on the comparator tubes have different numbers/ranges. The hue/colors on the tube appear comparable to me. The 7.2's for both tubes look the same. The 7.6 on the large is slightly redder than the 7.5 on the smaller tube. The R numbers are different, but I just thought that was due to the smaller sample size of the K1000 so the saturation/concentration would be different. If the R0004 is made for higher levels of chlorine, I would like to confirm that. I always thought the smaller kit was to serve as quick chlorine/ph check to save on the chemicals in the larger 2006 kit. Thanks

[chem geek]

I wrote to Taylor Technologies about this and they want the lot numbers on the two reagents (it should be printed on the bottle) so could you please post what those are for the R-0004 and R-0014 so I can let them know and they can investigate further?

[waterbear]

My guess is bad reagent if the K-1000 is always reading about 7.5 (orange-red). I have seen this happen before. How old is the reagent for each kit? The other possiblility is contaminatin (pissilbly from the TA) in the large comparator tub in the KJ-2006. Make sure that the tube is clean and rinsed out with your sample water a few times before you test.)
They should be testing exactly the same ( I use both all the time). If they are not it is most likely bad reagent or a contaminated or dirty comparator. Easiest way to check it to get new reagetns for both, they are not expensive.

[Cookieman]

Lot# for K1000 0014 is 2123C; Lot# for K2006 0004 is 3024B. I always rinse the tubes before filling with sample water or going to a different test, but maybe I need to do a better job....will try that. Both kits are less than a year old, but will be a year in Nov/Dec this year. Will order more of both. Thanks for the help.

[giroup01]

Reagents are fresh (approx 6 months to 1 year from manufacture date)