Thank goodness. I'm very glad to have such an ascertive diagnosis. I have a 55 gal aquarium. Approx. 8-10 gallons are displaced by substrate. Not much biomass to speak of, maybe 60% sq footage covered in microsword. I know that bubble counts are in large part useless, but should I be running 5-6 bubbles a second and still be low? I know I need a drop check to ascertain CO2 levels. I'm wondering is it simply that I do not have the needle valve open enough to introduce the required amount of CO2 or could it be something like highly dilluted gas from the supplier or ineffective exposure in the reactor? Does this flow sound low for my size tank? Even though it is an entirely innacurate way of determining good CO2 levels, it seems that there must be some avg. range of flow per given volume of water that typically provides enough carbon to produce an acceptable level of CO2 as referenced by the drop check indicator. Am I in that approximate flow range? Could it be some other problem with quality of my carbon source and or its delivery? Should I just crank up the gas?