co2 indicator question?

Unfortunately, those directions make things simpler than they really are. For your drop checker to work properly you need water of a known KH with no other buffers. That means distilled or deionized water with a known quantity of baking soda added. Most people use a 4 dKH solution so that the drop checker is green when the CO2 concentration is about 30 ppm.

You'll need to either make or buy this 4 dKH solution. There are directions on this board and elsewhere on the internet for how to make it. It's not that hard, but you'll either need a KH test kit or a fairly sensitive scale.

 

This should help you...

http://www.barrreport.com/articles/2661-drop-checkers-co2-indicators-why-how.html

 

It definitely doesn't take the drop checker 24 hours to start working. You might want to double check something. Take your drop checker out and clean out the bell portion of it on the inside -- you can leave the 4dKH solution in it. You may notice a scum (protein?) layer across the bell. If your drop checker stays green after your CO2 goes off (it will even stay green all nite), you can rest assured that you have the scum layer. For some reason, this layer causes the CO2 to keep building up -- there is no longer an exchange of CO2 with the water.