I started with a fresh water fill this year. After filling the pool and getting everything balanced other than adding cya, my readings were:
PH 7.2-7.6 (currently aerating and adding muriatic acid)
CYA <30 but should be 0 because none was added to this fill with pool completely dry before filling and test showed no turbidity)
Using poolcalculator.com, it calculated I needed 131oz dry stabilizer to get to 70ppm or 128oz for 68ppm. I bought 2-4lb containers of the Clorox brand stabilizer. I dissolved the contents of the containers(128oz) into a couple buckets of water and added it to the pool. It is said it could take up to a week to register on a cya test, but I was able to get all of the granuals to dissolve, so I tested the next day just to see. And to my surprise, my cya was a little above 100.
So, an error came in one or a combination of these ways.
1. I added more CYA than 128oz. I did not weigh the actual product and assumed each container had precisely 4lbs.
2. I have CYA in my tap water
3. I miscalculated my pool's water content by more than 20%.
4. The test created a false high reading.
Now to my actual question. Are there any conditions were one could get a false high reading using the black dot test? In looking around here, I've seen false low readings and false pool store high readings, but nothing really of falsely high readings. I am using a k2006 with TF replacement regents.