I ordered a bottle of the R-7065 CYA samples that is supposed to be pool water at 50ppm CYA level. I wanted to verify how close (good or bad) to accurate my previous CYA readings had been because I don't feel they have been very accurate based on the FC readings I get back.
When I used this solution in a CYA test, I personally tested this R-7065 to a reading of 30, not 50. I then tested my actual pool water and got a reading of 60.
How should I interpret these results? Should I use the ratio and assume that since my reading of 30ppm on what is a "known" 50ppm sample is a ratio of 3/5, that my actual pool water reading of 60 using the same ratio means my CYA is actually 100??
Or am I doing my baseline testing wrong. Should I use the known 50ppm solution and put into the black dot tube enough solution until it hits the 50 line, take a look at what the block dot looks like to my eye, and then try to hit that same block dot visibility when testing my actual water, instead of trying to wait till the black dot disappears?