Figure just for fuk sake I would round up some of the information that is readily available on the topic of 24/0 by well reputed growers of Cannabis or accomplished botanists for decades:
"It's been established for many many many years now that cannabis is a C3 plant.
It does not need a dark period. C3 plants gather CO2 only during the light period when they are photosynthesizing.
As long as the light is on, C3 plants gather and use CO2 for photosynthesis. Some growers practice a version of
anthropomorphism with their plants.
They believe that since people need rest, plants do as well. Concerning cannabis, this is not true.
Every grower can make a personal choice about light cycle. They can save on their electric bill or prolong ballast/bulb life. 18/6 can be less of a "shock" when changing over to 12/12 for flowering than 24/0 or heat issues can be addressed by fewer hours of light, but
basic botany has proven long ago that cannabis needs no dark period."
-Ed Rosenthal
"So far we have seen how light energy has been converted to chemical energy and stored in the high-energy compounds, ATP and NADPH. But we have not made any food for the plant. That happens in the next process, the Calvin cycle (named for its discoverer). The Calvin cycle does not depend upon light and can occur in either light or dark conditions, unlike photophosphorylation". <<<< PERSONAL NOTE: Perhaps this is where the confusion is for so many - notice that while the calvin cycle is independent of light, it can occur during light hours (it simply doesn't NEED light to do this). This actually speaks to the testament of the 24/0 during veg since you can maintain constant light, you receive 25% more lights on period [(24hr - 18hr)/24 possible hrs] = 25% difference.
Meaning 25% more photosynthesis takes place resulting in more growth in shorter amount of time.
"Here carbon dioxide from the air is used, "fixed", to make organic molecules for the plant, hence the name "carbon fixation". Remember that carbon dioxide is very low in energy and glucose is very high in stored energy. Where do you suppose the energy to raise carbon dioxide up comes from? You guessed it! The energy stored in ATP and NADPH in the light dependent reactions of photophosphorylation will now be used to power the Calvin cycle." <<<< PERSONAL NOTE: Meaning that raise of carbon dioxide is limited during the Calvin cycle to the amount of energy the plant is able to produce during photophosphorylation,
which only takes place when light is present. By allowing 24 hours of light over 18 hours of light you are providing more energy for your plant to use during the Calvin cycle which means more CO2 uptake and a more efficient use of the environment the plant is in.
- June Steinberg - National Lewis University
http://faculty.nl.edu/jste/calvin_cycle.htm
My final thoughts on the matter... The science supports the theory that 24 hours of light provides more energy to the plant for photosynthesis and for the Calvin cycle. This covers the plants growth above the dirt and beneath it. I will say however that without adequate CO2, the additional light will not be used
as efficiently than if it had more available CO2 - but still more than 18 hours of lighting because even with normal CO2 (non-supplemented) there is still CO2 available for the plant during those additional 6 hours - some is better than none..
This then leaves the argument of "is the cost of extra electricity worth the increase in yield. Personally, my electric bill increased a TOTAL of about $25/month when I started using 1000W lighting. Dropping 6 hours from that would save me 25% of that $25 = $6.25 savings a month. In a total grow cycle of of 4 months (say 8 weeks in veg, 8 weeks in flower) I stand to save $12.50 during veg if I go 18/6. If I yield a single gram higher (let alone 25% higher), the $12.50 is negated.
So then, let's say that your concern now falls on equipment (ballast life and lamp life). Based on my reading and personal preference, I see a lot of people change their bulbs around 6 months-ish (some go over a year without replacing it - again personal preference). That said, if you are burning the lamp 25% more during veg, then one could reason that instead of changing the bulb at 6 months and your veg avgs 50% of your grow cycle (3 months), you should change it 3 weeks sooner (12 weeks * 25% = 3 weeks). Even if your paying $100 a pop (high) for hortilux eye bulbs, your losing only around 3 weeks of life which would be valued at ~$11.50 - so now we're up to a total increased cost of $24 a crop.. So now we would need to yield a whopping 2g's more to offset the cost (less if you change your bulb less frequently than every 6 months). Finally, your ballast. Since I have no idea about the life of a ballast (never had one die on me, but that's not saying much, I've only been growing around 4 months), I can't say the overall net value lost that an extra 25% of light during veg would amount to, but it's going to last far longer than a bulb will, you do the math. Just a thought: If you're worried about your ballast, perhaps get a second one and have one on for 12, cycle it off while the other 1 comes on, so you are only taxing each ballast 12 hours. Both ballasts would live their normal life span. Granted the cost of an additional ballast may not be worth it to you, but it would prolong the life of both of them resulting in a long term net
savings.
In the end, as has been said many times, it all depends on what you feel is best for your individual situation. For me, I see the logic in 24/0 being better than 18/6 on both the plant growth front. I would also venture to say in my case, it actually SAVES me money in the end even if yield was not a single gram higher since my grow is in a custom built room in my garage - having the light on 24 hours means I don't have to have a 1500W heater going for 6 hours of lights off to keep my temperature from dropping under 60*F.
I don't smoke your bud, and your yield doesn't affect me. Your crop, your choice. Just providing sound research to backup a theory I subscribe to. Hope someone can use this information to make a better informed decision on what they choose to do with their light cycle during veg.
