Looking at this thread and all the dogmatic answers makes me SO glad I quit CO2 and went back to low-tech. I'm sure that there is some good information here, but my tank is finally algae free, lush, and green and I am pretty happy!
still trying to sell my CO2 setup, though!
That's fine and you could certainly have a very nice setup without co2, bu once you go that route you are limited in what you can grow and many times how well they grow compared to co2-enriched plants.
Sometimes it's a lifestyle choice and it's simply not worth it.