There are simply too many variables. We will however offer a guideline on where to start for a few different situations. People in the planted tank hobby use tanks from 1 gallon to 1,000 gallons and higher. 1 bubble per second might be perfect for a 10-gallon tank but will not be close to sufficient for a 120 gallon. A few variables that will affect your injection rate and saturation are surface agitation, number of plants, which plants you have, tank water volume, calcium hardness, tank pressure, what fish you have and often more. Not all fish are tolerant of hard water with a low pH.
Below are a few examples of tank sizes and an approximate injection rate. Use these starting rates along with your CO2 indicator to ensure you are reaching but not exceeding 30PPM and your indicator is not turning a yellow color. It is also important to note the reagent in your aquarium CO2 indicator will need to be replaced and exterior cleaned during your weekly water changes to keep the color bright and easy to read. 5 gallon, 0.2-0.4 BPS
10 Gallon 0.4-0.8
20 gallon 0.8-1.5BPS
40 gallon 1.6-3BPS
You may notice as volume doubles, so does the suggested injection rate. 1 bubble per second may be perfect in your 10 gallon, but could harm inhabitants of a 5 gallon at the same injection rate due to less water volume.