Test Kit results VS pool supply store numbers

[Motordoctor]

Hello all, got a Taylor 100 test kit as recommended by the forum. Been using it about a week now, the only test that is hard for me is the CYA test. It's hard to see exactly when the black dot becomes clear. But that's not my question. These are the numbers I came up with with the test kit. The sample was taken 1 ft below the surface and tested within 5 minutes. I ran the tests indoors. The pool is an above ground 12X24 with 7000 gallons. Hayward sand filter. The water condition is slightly hazy toward the bottom.

FC=5
CC=1
PH=7.5
Hardness=375
TA=130
CYA=85
Borate=30

Took the same sample to the pool store to see what they came up with. They use a computerized analysis (brand unknown) and here's their results.

FC=1.74
CC=.58
PH=7.3
Hardness=136
TA=98
CYA=28
Copper/Iron=0ppm
Borate=60

So my question is this: That normal to be that far apart? The only close one is the PH. Thanks for your help and suggestions.

 

[JasonLion]

Welcome to TFP!

That kind of wildly wrong test results is sadly extremely common from pool stores. Trust your own results.

 

[RobbieH]

Try watching this video and see if it helps you with the CYA test.
https://www.youtube.com/watch?v=NxaqoW-_MCs

Other than that, what Jason says above.

 

[Isaac-1]

Yep, you are starting to see why we say free pool store testing is worth less than what you pay for it

 

[Motordoctor]

Try watching this video and see if it helps you with the CYA test.
https://www.youtube.com/watch?v=NxaqoW-_MCs

Other than that, what Jason says above.

I was watching a couple of the other videos and I noticed that the video differs from my instruction RE the calcium test. Mine says 10 drops and the video says 20 drops. Which is correct?
https://www.youtube.com/watch?v=icawkIa8jtg

 

[zea3]

Computerized test results are often the most inaccurate due to the need for re calibration on a regular basis. The computer running the test has to be calibrated correctly in order give accurate results.

 

[Smykowski]

I was watching a couple of the other videos and I noticed that the video differs from my instruction RE the calcium test. Mine says 10 drops and the video says 20 drops. Which is correct?
https://www.youtube.com/watch?v=icawkIa8jtg

They are both correct. One gives a 1 drop = 10 ppm result, and the other gives a 1 drop = 25 ppm.

 

[Motordoctor]

They are both correct. One gives a 1 drop = 10 ppm result, and the other gives a 1 drop = 25 ppm.

The accuracy the same either way? The reason I ask is this: I added some calcium to the pool based on what the pool math calculator told me to add and the number I'm getting is much higher than what it should be. I think the first test I ran when I got the kit was 500 on the hardness measurement. Now I'm getting 375. One fact though: I added calcium based on the pool stores measurement (they showed it was low) since I didn't have the test kit yet. The pool store is still showing a low calcium reading while the test kit's numbers are high. Thanks for your help.

 

[duraleigh]

Some months ago, A group of TFP Pool Nerds decided a resolution of 10 ppm for CH was a bit too precise, wasted reagent, and served no meaningful purpose that 25 ppm resolution couldn't do. We simply changed the instruction cards in the subsequent new kits. All kits from June 1, 2014 or so should have the new 25 ppm instruction cards within.

 

[salinda]

I had some issues with the CYA test as well and haven't had great confidence in how I read the results. This has bothered me for years, so I watched the TFTestkit video AND I ordered the CYA standard solution I found at TFTestkits.net (http://tftestkits.net/R-7065-CYA-Standard-Solution-p34.html) and practiced a whole bunch with that until I found the lighting etc. that worked for me to get consistent results. THEN I started testing my pool water and I am much more confident.