Wait, that's ALOT? not trying to be mean or derail, but isn't the recommneded drops of ph inicator solution to be 5 drops?
And questions for the experts : adding more solution shouldn't make a difference should it? Shouldn't more solution actually darken the solution making it different to read than the general color chart of "yellow green blue"?
well.. adding more solution just makes the colour darker..
At a certain ph the indicator will always be the same colour (be it blue green or yellow). Adding more indicator just means the colour is darker. Personally I just find it easier to read...... I always aim for a green with a hint of yellow in my drop checkers.
I change mine every 4 - 6 months. Not because it no longer reads, but because I think I should . Just be sure you are using actual 4 DKH solution and not tank water as it will affect overall colour renditioning.