I ask this because I have a BioGuard test kit and I'm running out Phenol Red, and it seems BioGuard is out of the test kit business. Pentair sells a 16oz bottle already with chlorine neutralizer in it for $11 and change on Amazon. The concentration of Phenol Red I have is.065%, as stated on the bottle. However I don't see what it is for the Pentair. I use 5 drops of the phenol I have for sample size my kit takes. I'm guessing this is were the concentration of phenol you use makes a difference in accuracy?? So, is all Phenol Red the same?