What brand is the drop checker tell us more about your drop checker.
Are you using 4dkh water?
Are you using 4dkh water?
If it didn't turn blue when you took it out of the tank, then the solution inside the DC was contaminated somehow. Rinse it out a couple times with some clean 4dKH solution and then reload it and try again.Nope, it remained bright yellow for a couple days and then I poured it down the drain.