Thanks jcardona!
I have been wondering about "drop checkers' but no one has ever called them that, so I never knew that there is a fixture that can be put in the aqarium to constantly monitor the CO2 levels. I have heard it is the best way to test, but I couldn't find any info because every one just said "check with a 4dkh solution" , which means nothing to someone who doesn't know how the WHOLE process works. I have always been using BPS as a reference point (which REALLY isn't inidicative of ppm).
Just saying the term "drop checker" and "google it" has help tremendously. I now understand how they work and how to get one. Just ordered it. Thanks a bunch!