more due to how much you are injecting really. those little setup make use of calculations saying things like using '4 bubbles per minute'. Any unit can say this but in reality most people who use pressurised are using 1 bubble per second on anything around the 30 litre mark. Thats 20x what the little units suggest.
A little like the economy rate of fuel applied to cars. At a perfect X mph then yes the statements are right but in reality it is impossible to driver everywhere at X mph constantly even if you try unless you are on an oval race circuit and cruising at that mph. The reality is that even if we try to stay on that mph we will be slightly above it or below it, plus stopping starting up again, queuing etc. However it sells cars to say it does X mile to the gallon. More useful would be a full list of how many miles to the gallon the car would do at every increment, how much it uses to start up, how much it uses whilst in neutral or queuing, temperature variance, how much the air onditioning etc uses up
Some cars may be better at X variance than another but poorer than the same car at Y variance. Same with X aquarium setup versus Y setup.
Tanks have all many many variations like the above analogy, where water evaporates creating slightly more turbulence meaning more needs injecting, where KH and other parameters play their part, where other variants and reactants play a role in determining how much you can use, however 4bpm? May as well use a very slow DIY mix if that suggested rate worked.
For me on my 125ltr I use circa 2bps. less than most people with the same tank probably from variances within my system compared to others. On my 23 ltr I was using 25bpm to achieve the same ppm. Thats pretty much close to the ratio calculations of 125ltr vs 23ltr. My 23 ltr would use a 22g cylinder up in a few days I would expect.
