A few facts and opinions re: co2.
It is not flammable or combustible. People also think that oxygen is flammable because of the signs in hospitals "Oxy in use, no smoking". C02 does not burn, and neither does oxygen.
C02 is a great addition to a grow IF everything else is dialed in. If you have your feed just right, and lights just right, and everybody is happy ... add C02 and watch it go into over drive. If you add it before everything is dialed in, you'll have a mess to straighten out.
I've used both canned gas, and generated. They both have their positives and negatives. Burning makes for heat and moisture, so you need to run a dehumidifier, and that makes more heat too. Canned is 'cleaner' but more expensive (in time and expenditures).
A carbon monoxide detector is not needed, because you are not generating carbon MONoxide. You are using carbon DIoxide.
Two molocules of oxygen.
Carbon monoxide is very poisonous.
Carbon dioxide is not at all poisonous.
It would take a LOT of carbon dioxide to hurt you, and it would be from displacing oxygen and a mammal would suffer from suffocation.
Use CO2, but add it last ... after everything else is balanced and running smoothly ...