Do not POUR into the view tube.Ok, lol. Let me just double check then. Fill the bottle with the red cap as if doing a regular CYA test. Then dump half that out and replace with tap water. Then pour into the CYA view tube as usual.
You need to squeeze through the nozzle.
This adds additional agitation which will result in you reading a higher (accurate) CYA level.
Don’t ask me how I learned about this…