I am doing a similar experiment. This all came about because I was arguing about why so many people lost their phals to root death less in a short time after purchase. My CO2 generator is very primitive at this point. Champaign yeast and sugar water. I plan on creating a better generator shortly. The phals are enclosed in a plastic tub now to keep the CO2 gas from wandering off. I am very interested in the dark CO 2 fixation, the diurnal acidity rythems, CAM and creating the correct modified xerophytic conditions. But also, the whole question of keeping orchids healthy and growing. Not a scientist either. I would love to compare notes and get in on the club.

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What about the CO2 released by decaying biomass?

Here's a few photos of the growth over the last month.
Co2 is still set to 1500 ppm.
photo taken April 14th 2014
Phal cornu-cervi.

Photo taken today May 13th 2014
Phal cornu-cervi

Photo taken April 14th 2014
Phal lueddemanniana

Photo taken today May 13th 2014
Phal lueddemanniana

I'm glad your giving it a try. Any positive or negative results you may have please feel free to post them in this thread.
I do have a question for you thou. How do you know how much co2 your giving them?
I was surprised how little it took to raise the co2 in my grow tent just breathing in to it, 7-10 exhales and it was close to 1500ppm. I found that out after I got the co2 controler. You can pick up a co2 monitor for around $100 off ebay. The autopilot.

They look like that they are growing well. The newer leaves looks a bit greener than the older ones. Did you change the light, too?

Bravo, the plants look healthy.

Phillip M, good question. so far I have not seen any discussion about what happens if they get too much CO2. What they are getting now is negligable due to the primitive nature of my equipment at the moment. I'm sure without directed hoses and so on, much of the result attenuates into the atmosphere. I am thinking in terms of decaying biomass. I am definately studying plans and protocols, but my main purpose is to stop losing orchids, phals especially. I do not seem to have as much problem with other kinds.

Nexogen, thank you.

Optimist,
Their where a couple of studies if I recall on super elevated co2, they were 10,000 and think 50,000 ppm were used.
I'll try to see if I can find them.
Have you looked for information on decay and co2 production.