Dry ice is a rather expensive option as previously mentioned. Yeast/sugar gives off relatively small amounts of CO2 compared to what plants would consume. Vinegar/bicarbonate of soda is also a relatively expensive way to go as far as the amount of CO2 generated and the chemicals need to be constantly refreshed.

If one wants to go with CO2 enhancement then investing in a 20 pound tank with a regulator is likely the best option for most people and will be a cheaper option long term. Also, CO2 with a tank can be regulated to give off the amount of CO2 needed which is important for efficiency.

With dry ice who knows how much is being given off unless you measure the mass over time and do the calculations. It would also be difficult, for example, to set up a block of dry ice to raise the level of CO2 in your grow closet to a roughly optimal 1500 ppm and keep the levels there like a tank/regulator of CO2 can. A 20 pound tank costs about $15 to refill.

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Talk, without the empiricism to back up your statements, is dogmatic BS.