accuracy of Leslie's vs home taylor?

[GoofyYno]

I Finally got my TF-100 test kit a few days ago. I did the tests today, then brought some water to Leslie's to compare with their test. They were way off! I got : PH 7.8 and Chorine of 1-2 on the quick OT test. on the more accurate DPD I got FC 2; CC 0.5, TA 110, CH 560; CYA never worked- I could alway see the black dot till the red tipped vial was empty, and cylinder was overflowing. the results from Leslie's were: FC 0.5, CC 0.5 (he said they were barely visible, but >0); TA 80; CH 300; CYA 20; PH 7.4.
I would normally assume I was in error, but with new reagents (never in the sun), and test which are easy to read - color changes after a drop is not very subjective. (I carefully measured each sample and did both tests within 30 min.
I do believe the CYA is low, so I added some. I have questions as to why the drop, But I added them to another thread.

 

[jblizzle]

They were not as off as some we have seen ... but not very good either.

CYA of 20ppm is really the minimum of the test so could be anything less than 20ppm ... which matches your test. Definitely sounds like you need to add CYA.

And trust your own kit

 

[Bama Rambler]

That's a classic example of why we harp on people to get their own test kit. You never know how bad they're going to be.

 

[Isaac-1]

Remember the CYA test is considered only accurate within about 10 ppm, a lot depends on light conditon when reading it, for best results view in daylight with the sun to your back, so at least you were both close.