Hehe. Drop checker is not the best indicator. I do have one in my tank though for a quick glance. PH drop and KH levels supposedly have the best indication to CO2 levels. Anyway it's a lot of science I'm not too sure of
. Hoping this has helped you in some way.
Yes the drop checker seems very useful and at the very least safety net to alert to a potentially harmful situation.
I am almost certain I have phosphates in my water (have a test kit on the way), according to that post link you sent, that might screw my calcs a little.
Thanks for all your help! Got me on my way.