Having used both systems, I don’t feel these systems can really be compared in this manner - whatever maths you may’ve used, distribution of the CO2 in the tank is completely different between the System 60 reservoir method and the Nano in-tank diffuser methodThe purpose of this exercise was to compare the delivery rate of the Tropica System 60 to the the Tropica Nano kit. After my cheerful maths and dcurzon's adjustment and assuming 0.11mg bubbles, the System 60 seems to do 3-4 bubbles per minute.
30cm cube, moderate substrate, hardscape, Eheim MiniUp filter, ONF Flat One Nano + (love this light!)
there's no solenoid, so presumably its on 24/7, but they use a very low bubble count perhaps in light of it being 24/7
0.109mg per tropica bubble