C02 is a heavy gas. Therefore, it is better to dispense it from high up in the grow rooms for all methods. The desired C02 parts per million is approximately 1,500PPM: 1,100 coming from the apparatus and 400 from the outdoor air.
Carbon dioxide is most needed in the first few hours after the lights turn on.
CO2 Production Methods
Buying a propane generator or C02 tank is probably the easiest way to get the desired C02 of 1,500PPM without using testing gear. Buying the machine preset to release the desired volume when leaving the store is important, and double-checking the figures before operating the gear is necessary, too.
However, a grower should keep in mind that the generator adds heat and moisture, which may help in the winter months. Altering the climate should be considered if the range goes off somewhat.
For example, humidity may rise above 60%, and therefore adding a dehumidifier or adjusting the system will lower the humidity to 40 to 70%. If a propane generator is used for the first few hours in the morning, this added heat and humidity will help open up plant stomata so that carbon dioxide intake is heightened. The propane generator can be used outside the grow room and a fan can be used to draw the carbon dioxide into the room.
A disadvantage of using CO2 is that the exhaust fan must be shut down every time the CO2 is being dispersed for it to be plentiful and useful to the plants. Often, the humidity rises first thing in the morning in rooms without high tech climate control. Therefore, the carbon dioxide intake can be more effective. Many growers add carbon dioxide injections for the first part of the light cycle. Some of the best grow rooms have used only the CO2 from the great outdoors by having really strong air-intake and exhaust.
C02 can also be purchased in a two-part kit from hydroponic stores. When the powder and reactor are mixed, C02 is dispersed: it’s cheap and easy. Supernatural Excellofizz make pucks for closets. Room temperature water is poured onto a puck to make carbon dioxide. One puck per day is used. They come in packs of 15 or 50.
One more method of producing C02 is to make a water / sugar solution that drips into a lower reservoir. The lower reservoir will contain the yeast, and a water / sugar or water / molasses solution. This solution can be made to a pH of 4.0 to 5.0, which is the proper level for beer, wine, and bread yeasts. However, it will work fine if left alone.
The lower reservoir will be producing the C02 since it contains the yeast.
The lower reservoir should have one hole near the bottom for a siphon overflow hose. The top of the hose will be the height of the reservoir.
A second hole should be made near the top of the lower reservoir for carbon dioxide-enriched air to escape. This hole must be higher than the siphon overflow hole in the bottom. It can be covered with panty hose to keep out fruit flies.
One of the holes in the lid of the lower reservoir will be used to allow the solution to pour in drip-wise.