PH results change every time I test

Did a test 8.0. Did one right after 7.6. One right after 7.2.
So your pH is changing within minutes between tests? That's not really possible unless you are dripping a gallon of acid in the pool each time. You don't say how big your pool is but pH cannot change like that unless you are manipulating it in some way.

I assume your pH reagent is reasonably fresh and has not been laying in the sun.
 
Do test. Get 8.0. Immediately drop out sample. Get test. 7.0. Drop out sample. Do test. 7.8.

Etc.

I did notice some weird stuff when I retested last time.

Somehow my CYA rose to 70 from 50. TA was 100 from 70 (prob just ph adj).

FC 7
TA 100
CYA 70
PH 7.8

(Last test)
 
Does the water level of your sample matter for pH measurements? I was under the impression it didn't really matter that much, but it would be the only test in the kit that didn't need a perfectly sized sample.

But if my theory was correct, I wouldn't think a small variance in sample size would NOT cause you to get 8 one minute and 7 another.

One other shot: do you happen to have another test kit of some kind and have used the bottle for it in your Taylor K2006 kit comparator tube? I have a Taylor k-2005 or something or other, and once used the phenol red from that kit, and got a way higher pH reading. But I quickly realized my error.
 
I have never experienced any variance in my K-1000 test (that's just the part number for the color match blocks and reagents that come with the TF-100 and K-2006). I try to fill consistently to the line mark but I am routinely a little high, a little low from time to time. In fact this week I was starting to get "worried" because every time I've tested in the last 3 weeks my pH has been getting the same shade, just more yellow/orange than the 7.5 color.
 
I just looked and what I have is the K1001. The phenol red that comes with it is different than the one that comes with the K2006. As are the comparator tubes.

I kind of like having both kit tubes, because the kit from the K1001 has most of the measurements that are in between what the 2006 reads. When I feel like I'm in between readings on the 2006, I pull out the comparator tube for the 1001 and can usually find an exact match on it's color scale.
 
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