I have the ULR standard and it reads the same every time. I suggest you get a standard if you want to verify accuracy. After that any variation might be assigned to testing procedure accuracy.I have a question about running the Hanna Checker Phosphorus test:
How many times do you run the test with the same sample?
I ran the test and the 1st result was 17, then I decided to run it a couple more time just to see. I have 2 vials(one with sample and one with tank water) and just kept rerunning the test for a few times.
Here are the results
1. 17
2. 7
3. 5
4. 4
5. 7
Which number should I use? Or do a avg of them all?