CO2 is a bit like a drug addiction that hobbyists get hooked on. That's fine, but this non CO2 approach will give an excuse to have another tank that needs less attention and is cheap.
I suggest folks coming from either the non CO2 or the CO2 enrichement approaches to give the other method a try and see what benefits it has.
CO2 and non CO2 tanks work for all the same reasons, but........
They grow at different rates.
Based off of my testing, I'd estimate close to 5 to 10 times slower than a CO2 enriched tank at 2-3 w/gal.