One still in the closet.

Started feeding her this week. Also pinched out the top. Started an experiment; I made up a 1 gallon jar containing fermenting water/sugar/yeast, this produces bubbles of approximately 0.5 cc of carbon dioxide. Having figured out the volume of the 60x60x140cm grow tent, my very poor math and a spreadsheet tells me the CO2 level will be raised to 1500ppm in about 30 minutes at the current rate of fermentation. I am waiting for a CO2 meter to arrive so I can see what's really going on in there. Everything is very approximate, very very approximate. The tent is ventilated by an extractor fan every 2 hours. Generating CO2 by fermentation is interesting because fermentation - and therefore gas generation, increases with temperature to about 30C. The amount of gas generated can also be controlled by adding more or less sugar to the mix or filling the jar more or less full with the solution. Gas production tails off over some days as the sugar gets used up. my plan is to swap the jar every few days to keep something like a constant gas production. Dried bread making yeast from the supermarket is cheap and easy to find. I think wine making yeast might be better but I haven't tried it yet. Any sort of domestic granulated sugar is fine, Currently I am using about 500grams or just over 1lb per week, it's early days though so that figure is more guesswork than fact. Temperature in the tent is now increased to about 30C by wrapping it in a couple of old sleeping bags. All heat is provided by a 120W LED grow lamp at about 1/2 power. ambient temp is around 15C The idea is to speed up growth without adding to the cost significantly. I'm pretty sure it's not likely to do any harm even if the experiment doesn't produce a measurable gain. I think the greatest benefit is likely to be during flowering, If this process improves yield by even a gram or two, it will have paid for itself. That's the theory anyway. We'll see how it pans out in real life. ***Edit, some few days later,,,, The CO2 meter arrived, Pretty good so far, 2 litres of gently fermenting mixture raises the level to 1500ppm in a couple of hours. I don't even know how much diference it's going to make, but it's pretty clear that it will be possible to maintain a substantially higher CO2, I think it should be possible to keep a fairly consistent level of CO2 by adjusting the volume of fermenting mixture. I plan to keep experimenting, according to the internet, it may not do much good but it's unlikely to do any harm. Some people say increased CO2 makes the plants more sturdy, others say it makes the plants grow quicker. ***Edit 2, A little more solution in the jar keeps the CO2 level around 2000ppm fairly constantly.