I think those two are thinking about CO not CO2 but if your burner is messed up it will put off CO so its not entirely a bad idea.

As far as doing hydro without an EC or PPM meter.. the best I can say is one day your luck will run out..

Where do I find the cheapest ppm controler, and how much is it, and do I want to buy the cheapest one?

eb-ay $35 telair ventostat.. maybe another $5 for the cable so you can change the setpoint from factory 1100ppm to your desired ppm level
Aaron385 Reviewed by Aaron385 on . Best mounting position for co2 generator Today I got something that I have been wanting for a couple of years now. A co2 generator and the various other stuff you need with it. Yippie! All Green Air brand, all from a hydro store. (I know, I'm crazy.) My wife isn't thrilled, but now I get to see if the claims of 20 to 40 percent increase in yeild are true, along with the claims of earlier bloom time. I'm not looking forward to the work involved in tearing apart my grow room and rebuilding it, but I am looking forward to finally getting Rating: 5