"SOME PEOPLE SWEAR BY CO2" The high cost of CO2 enrichment setups are costly, so I have researched, tested, played with sodium bicarbonate, vinegar, sugar & yeast and this is as simple and cheap as I can get, to do some testing on the CO2 Injection Enrichment. I have come up with a Do It Yourself CO2 Enrichment Generator, the described set up is an inexpensive way to observe first hand the benefits of CO2 injection on plant growth. I personally had never seen what CO2 could do for a plant before , and would probably never have purchased a conventional CO2 injection system because of the high cost. In fact, I still haven't purchased one. I find the this method adequate for my current needs.
The first step:
Find 1 gallon milk jugs , if your doing a closet grow 1/2 gal jugs will be fine as in demo photos. Fill the jug with 6 cups of water (3 cups for the 1/2 gal size), now use a permenant marker and draw a line at the water level (this is the fill line for the sugar water, now discard water in jug). Get a 16 penny framing nail heat the tip of the nail and poke 10 holes in the jug 1 - 2 inches above the water level and in a straight line parallel to the water line (see photos) these are the CO2 gas discharge holes.
The second step is to create CO2. I mix 3/4 cup sugar, 6 cups water and a pinch of yeast (roughly 1 teaspoon does the trick). The exact ratio of ingredients is not critical. (cut amounts in 1/2 for 1/2 gal use)
Using the above mixture, I regularly get 10-14 days of CO2 production. When the system stops bubbling (the drop in gas production is often precipitous), dump out everything and mix up a new concoction.
You can see the active CO2 escaping the surface in the photo below
This CO2 Generator DEFINETLY WORKS a test has been done on an enclosed generator, connected to a aquarium hose, the other end of the hose in a jar of water,and the gas is emitting at a rate of one bubble every 3-7 seconds under enough pressure to operate @ a depth of 8 inches, a sufficient rate to satisfy my continued testing.
Now suspend the CO2 generator above the plants (CO2 is heavier than air) as the CO2 is generated it begins to build pressure and fills the plastic jug untill it reaches the discharge holes (the CO2 pressure in the jug keeps pushing the CO2 out the discharge holes)and begins to spill out over your plants.
Hot water kills yeast. If you dissolve yeast in hot water (like what comes out of my gas water heater), you probably won't get any CO2 from your setup. If you've mixed things up properly, you should get CO2 production within a few hours, possibly more quickly; I've sometimes had things going 30 minutes after mixing a new batch.
Here's what I do:
Fill a 2 cup measuring cup with hot water, and dissolve the sugar in it. Add three more cups of cold water to the mixture and mix it up.
Dissolve the yeast in a cup of cold water and add to mixture. I've only used bakers yeast, but others should work too.
Add more cold water to mixture to fill to desired level. Cover the gas discharge holes with your hand & Shake the mixture well.
Let sit at room temperature for a few hours until the mixture reaches room temperature. That's often all the time that is needed to get initial CO2 production going.
Some batches of yeast take longer get going than others. For example, yeast stored in a refrigerator takes longer to become active than yeast stored at room temperature. Letting the yeast sit out at room temperature overnight before adding it to your mixture reduces the startup delay. Another suggestion (from homebrewers) is to hydrate the yeast in a cup of warm (80 degree) water for 20 minutes before adding it to the sugar mixture
I am still experimenting with exact ratios of sugar, yeast and water. In my system, the rate of CO2 production is relatively steady for a number of days, but then drops precipitously (from several bubbles a minute to no production in 24-48 hours). I suspect that the yeast exhausts some trace element or other critical ingredient. Yeast needs a number of elements, including nitrogen (e.g., ammonia but not nitrate), magnesium, phosphorous, potassium, calcium, zinc, iron and copper. My initial hypothesis was that a buildup of alcohol limited yeast production. However, a homebrewing friend reports that it would take roughly 3.75 cups of sugar in a 2-liter bottle to produce enough alcohol to reach a concentration of 15%, the point at which no strain of yeast can survive. As another data point, I have been running a mixture now for over six weeks that is still producing an adequate amount of CO2. I have no explanation for the longevity of the current mixture. I used the same general recipe that previously worked for only two weeks.
It should be possible to culture a new mixture using yeast from a previous batch. Simply save the sludge that collects at the bottom of a mixture. The top layer of sludge, which should be a bit lighter in color, consists of live but dormant yeast cells. The darker layer underneath is dead cells. I have not tried this myself. For more information, look towards the homebrewing field.
In summary, the described sugar, yeast and water CO2 injection system provides an inexpensive way to experiment with CO2 in a plant grow room. It is particular attractive to those interested in trying CO2, but skeptical that benefits justify the cost of conventional systems. Although a bit more hassle to maintain than a proper tank-driven injection system, I do not find the burden to be excessive. Although I could afford to purchase the more expensive conventional system, I have little inclination to do so at this point. I spend much more time fussing over my plants than I do fiddling with the CO2 Generator rig & frankly I'm still undecided as to the affects of CO2 enrichment, at this time, part 2 of the experiment is to determine actual appreciable enhancement with the use of CO2 injection.
This is still experimental so you will need to adjust the number and placement of your CO2 generators. If infact I find in testing with these prototype CO2 Generators, that IF THIS IS beneficial I may revise my CO2 generator tank to utilize 4" PVC pipe as in diag below for better dispersement across the grow rooms
I also believe it best to turn the "Exhaust fans off" during CO2 period so that all your CO2 is not exhausted immediately out of your grow room before the plants can benefit from the CO2 enrichment. the lites also need to be ON when you turn off the fans this is the optimum time to utilize the CO2 during photosynthesis. and lastly I also believe that the plants may now need a bit more nitrogen to keep all plants growing at full steam with the increased growth demand from the CO2.
This Co2 enrichment system is very easy and cheap, I'd be interested to hear any results any of you find, if you decide to try the experiment "SOME PEOPLE SWEAR BY CO2" we shall see?