Jason,

DC green is shorthand for stating that my drop checker (DC) filled with a 4kh solution shows a nice green color.

I have several of them and move them around the tank to ensure adequate c02 (I hope) all over the tank.

Per our measurements, this is between 30-40 ppm of c02.

This is not exact science, but what we hope to get.

This is an indication that c02 levels are adequate, but not confirmation.

It usually takes between 2-4 hours for the color to reflect your tank. That is why they are an indicator only...........