I recently bought Taylor's FAS-DPD test kit and I'm not sure if I'm calculating cl levels correctly.

Over the past week, I have been getting "permanent color" change after adding one maybe two drops R-0871, and have assumed that my cl levels were still low despite being able to slightly smell cl while in the pool and having some eye irritation while swiming.

When I tested my pool water this evening, I saw a "permanet change" after the first drop, AGAIN. However, tonight I was distracted and noticed that after a couple of minutes of allowing the 10 mL vial to stand alone that the solution changed back to pink.

I added a couple more drops, shook solution, and again "permanent change". Let it rest a couple of minutes and noticed it changed back. I let the sample rest for over an hour and it became a dark pink instead of a light pink as it has always been.

How long am I supposed to wait for a color change back to pink before making the determination that the change is permanent?