Hi all! My fas/dpd kit has worked great since I got it a few weeks ago. All of a sudden yesterday, when I put the powder in, it didn't register at all. My brain almost broke, lol. I added a few drops of bleach to a new water sample, then added powder again. The powder itself initially turned pink, but the water didn't and then all went clear again. I can't remember what I did next, but the next sample worked like it always has. Now today it registered zero again. Any clue what's happening? The only thing I've done differently to the pool itself is add some calcium two days ago to get the level up.