CO2

[Jim Reed]

Without investing in a small tank of CO2, would a 2 liter bottle of soda water with a pin hole work the same for about a week? Thoughts?
This would be for a small cold frame greenhouse.

[Eric Warwick]

There are natural ways of making Carbon Dioxide. One is mixing baking soda with vinegar. These are relatively inexpensive, and can be configured to go in the water as CO2(aq). Note: this will decrease the pH of your water with Carbonic Acid being produced from the adding of CO2 to the water. Water is also created in the process. Other ways of making CO2 is burning something, which is a bit more fun, but 100 times more dangerous.

[Vlad Jovanovic]

Sugar and yeast should work as well. .

[Jim Fisk]

How much difference does adding co2 make? Can one see the difference in plant growth? How about an unvented gas heater in the GH? Or venting the gh woodstove into the gh during the clean burn cycles? I would think that would be better than subjecting the fish to more co2.

I am addicted to the great subjects on this forum:-) and reluctant to use the provided smilys as they do strange things like change the type to blue???

[Vlad Jovanovic]

Well at 3-4 times ambient (300-400ppm) CO2 concentrations positive enhancement effects have been shown to be "significant" (at 1200-1600ppm). This doesn't seem to hold true for all species of plants though. But since most of what us folks would be growing are C3 type plants, you'd probably see some benefits. Above 2000+ppm CO2 is toxic to plants and not much good for our hemoglobin either :)...

Its much heavier than air so depending on your greenhouse design/vents, you may want to introduce it above your canopy instead of from below (like if you don't have roof vents).

CO2 ONLY benefits plant growth in conjunction with light...so no benefits to be had by night time gas heating or whatever...The rate of CO2 depletion is directly correlated with the rate of photosynthesis,with the depletion occurring rapidly within a few hours after daylight. People like Benton Jones Jr. have noted drops of 50ppm just after dawn, this has been observed by other folks as well. (i.e Harper et al., 1979...Carrathers, 1991–92)...

You might want to buy or make a simple CO2 monitor for your own safety and to see what kind of numbers your hitting with whatever CO2 production method you are using...

Also, Jim Reed if you go with a bottle type generator you might want to employ an extra bottle filled with a bit of water, and a piece of aquarium tubing, and some caulking. Get the CO2 to travel from the bottle where its being produced through the tubing and under the water line of the second bottle. That way you will always know when your CO2 generating method is spent...as there will be no more bubbles pushing out of the tube and into the water of the second bottle...hope that made sense. I've not really noticed any big difference personally...but it's not something I've ever done an even remotely 'scientific' side by side on. Certainly couldn't hurt though...

[Jim Reed]

I hadn't thought of that extra bottle idea. Thanks. Perhaps ill wait till there is more growth before adding co2, as to not suffocate the plants.

[Jim Fisk]

Vlad you rock along with the other brainiacs on here. I have learned more on here than all other forums combined. I finally found where the pros hang out. Thanks

[Roger]

I'd definitely hold off Jim.  I've grown in my basement three years and never introduced CO2 (besides passive, ambient).  Plants seem to always do well.  Just make sure your lighting is sufficient as well as your ventilation.

Jim Reed said:

I hadn't thought of that extra bottle idea. Thanks. Perhaps ill wait till there is more growth before adding co2, as to not suffocate the plants.