No, I don't have a CO2 meter. Wish I did though.
Question is, can you grow 15 pounds a month? Guess if you did bags instead of trays and worked it like a full-time job you maybe could - but you could also grow 15 pounds of weed with way less work, and have a way easier time selling it, for more money.
Have you ever grown mushrooms? 15 pounds of mushies are WAY easier, and faster to grow than 15 pounds of weed. Hands Down, No Questions. Mushrooms also cost pretty much nothing to grow. 15 lbs is 250 bags. Bags, coir, compost, and birdseed. Doesn't cost hardly anything. Total stealth. No high electricity bill. 6 weeks from the time you inoculate your birdseed. As far as selling it, it depends again on who you are, who you know, how good your shit is, and where you're at.
Is growing mushrooms better than working at McDonalds? Probably.
Is it better than growing weed? No. At least not unless you can automate a big chunk of the labor, and even then the money is probably better spent on weed. Guess once weed is legal, mushrooms might be the next best thing, but the demand won't be the same.
I like em both, BUT... I'd actually rather run mushrooms than weed. I can go on vacation for weeks and they need Nothing. Mushrooms are pretty much set and forget unless they are fruiting.
A 55 gallon drum, and a water heater element for pasteurization isn't hard to come by. By labor you mean stuffing bags with bird seed/ substrate and stapeling them closed........ Listening for a timer, emptying pressure cooker, and refilling with unsterilized bags.......
Boil your seed and put in bags.
Sterilize bags.
Inoculate your seed and forget about it for 10 days.
Massage the seed, and forget about it for another 5 days. (optional)
Pasteurize your substrate for 250 bags all at once in a 55 gallon drum, let it drain and cool a bit.
Load each bag with 25 ounces of substrate and equal amount of spawn. Shake, and staple closed.
Leave for another 15-30 days, and pick.
Even growing weed in soil requires a hell of a lot more attention than that. I've got to check hydro everyday. No vacations. I don't even THINK about what the mushrooms are doing unless it's harvest time.
Guess it's a matter of personal preference.
Peace.
Tav