On the chlorine drop test, I noticed something strange. I'll put a tiny spoonful of the test powder and mix it. I'll put drops in until it's completely clear (not even the slightest hint of pink). Say that's 13 drops for 6.5ppm. As I'm typing in the log, I look up and notice the mixture is starting to turn pink again (very lightly). I'll put one more drop in for 14, it goes back to clear. If I wait another few seconds, it starts to turn pink again and looks like it needs 15 drops.
Even with a silica packet in the powder jar, it still tends to crystalize. If I had to guess, it takes a while for those bigger chunks to dissolve and that explains why it keeps turning to pink after I've completed the test. I do make an effort to let the solution mix a bit before I start the test (maybe 30 seconds). But not always.
What is the cause of this issue? Should I ignore it? Usually it means a 1.0 - 1.5ppm difference, so I'm not sure.