Join Date: Aug 2006
Location: Jersey City, NJ
FYI i had the exact same problem of the dropchecker not turning blue after it turns green with well calibrated solution.
It turns out it does turn back to blue but only after 2 days. Basically i took it out of the tank and put it in a cup with regular tap water and the dropchecker remained green and i couldnt figure out why. It stayed green for about 2 days then turned back blue gradually, then i put it back into the tank and it turned back green in a few hours.
I think the problem is putting too much indicator solution into the dropchecker which caused the solution to react very slowly, i dumped in about 75% full, try only putting in 25% full and you should see it change back to blue faster if having the same problem.