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You can use the data in that paper to show how effective low levels of added CO2 can be. The data, in a different form is:

If you graph this data you get:

Note that doubling the ppm of CO2 from 3 to about 6 ppm triples the growth rate at very low light - 25 PAR - and an even smaller increase in CO2 results is as high a growth rate as you can get with that much light. Clearly there is a lot to be gained with non-high light tanks using the relatively small concentrations of CO2 that you can get with DIY CO2.

Re-graphing that data:

This shows that even for medium light a small increase in CO2 is very effective. You get as much improvement with as little as 10 ppm of CO2 as you do with much higher CO2 levels. This encouraged me to start using DIY CO2 on my 65 gallon tank.