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 erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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 18 vs 24 Hours of Light in the Vegative Cycle 
#4843 - 04/21/08 10:40 AM (16 years, 7 months ago) |
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Most green plants are classified as either C3 or C4 which represents how carbon(C) is used during photosynthesis.
C4 plants temporarily store carbon dioxide(CO2) over the dark period to use for photosynthesis during the day. C4 plants slow down photosynthesis once the stored CO2 is used up and they need to gather it from the air. Which is why trees slow down photosynthesis in the afternoon even though the sun is still bright. This does NOT apply to cannabis.
C3 plants(cannabis/veggies) gather CO2 only during the light period when they are photosynthesizing. During the dark period these plants only use oxygen for their metabolic life processes. They don't uptake CO2 , nor do they use it. As soon and as long as the light is on, C3 plants gather and use CO2 for photosynthesis.
C3 plants also have the ability to use higher concentrations of CO2 than what is found in the air. If the light is bright enough and the plants have sufficient nutes, their growth rate will accelerate from it(2000ppm vs. 400ppm of CO2), which increases yield. They can do this continuously, without a dark period throughout the vegetative stage.
The dark reaction is a process of photosynthesis that takes place in both darkness and light. It uses ATP and NADPH molecules that hold energy absorbed from light to break apart CO2 into it's base components.
Again people get anthropomorphic with their plant needs. People need rest, so plants must too. This is false as well. Light means growth. Scientifically. Although 18/6 will shock your plants less when you switch to 12/12, it's a personal choice whether you would rather sacrifice a little growth for a quicker adjustment or less photo confusion. If you want to save money or energy that's a personal choice too. Do what you need to do to make your growing scenario work.
Another factor to consider, your bulb life will be shorter the more you turn it on and off.
Don't confuse internode stretching in the dark cycle with plant growth.
Under 18/6 you may get a taller plant, but the end weight is less than a plant grown under 24 hours of light.
At 18/6 you will save some money on electricity,
but like i said before, 24 hour light means 24 hour growth
as long as the plants other needs are met.
24/0 will always show faster growth
as long as you are providing for the plants other needs.
Marijuana does not need rest.
It does not get tired from to many hours of light.
its keeps on photosynthesizing at the same rate through the entire light cycle.
Although more hours of light does mean higher temp. issues.
I think some people have better luck with 18 hours because of the drop in temps it provides the plants, especially to the root-zone.
Water, CO2 and nutrient requirements are increased under 24/0 .
The daily voltage spike at startup contributes a large portion of the wear on a lighting system.
One week before flowering you can reduce the photo-period to 18/6 to reduce the stress on the plants.
Normally, under ideal conditions you can flower plant about a week earlier when grown under 24/0.
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ecto
prop215 / sb420 patient
Registered: 04/20/08
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Loc: california, usa
Last seen: 16 years, 7 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: erb]
#4870 - 04/21/08 10:56 AM (16 years, 7 months ago) |
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how many more times are you going to post this?
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: ecto]
#4897 - 04/21/08 11:19 AM (16 years, 7 months ago) |
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I thought alot of people would have this question so I started a topic on this specific subject.
So this way i wont need to make anymore posts on this subject.
sound like a good idea?
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Sirius
Saturn Ascends
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Posts: 1,540
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: erb]
#5143 - 04/21/08 01:39 PM (16 years, 7 months ago) |
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Quote:
erb said:
So this way i wont need to make anymore posts on this subject.
sound like a good idea?
Its a good idea, but there will always be countless newbies asking this question. At the very least, now all you'll have to do is post the link to this thread. 
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 niteowl
GrandPaw
Registered: 04/20/08
Posts: 4,781
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: erb]
#6055 - 04/21/08 07:49 PM (16 years, 7 months ago) |
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The Ego is a pathological conditionlike a calcareous tumor or cystthat begins growing in the personalityin the absence of hallucinogenic substances-Terence McKenna-
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Yrat
Happy Planting
Registered: 04/20/08
Posts: 886
Last seen: 10 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: erb]
#8322 - 04/22/08 10:56 AM (16 years, 7 months ago) |
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Quote:
erb said:
[the dark reaction] uses ATP and NADPH molecules that hold energy absorbed from light to break apart CO2 into it's base components.
this is not true. CO2 IS a base component. Energy from ATP and NADPH is used to construct carbohydrates from CO2 and water.
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 "Prohibition will work great injury to the cause of temperance. It is a species of intemperance within itself, for it goes beyond the bounds of reason in that it attempts to control a man's appetite by legislation, and makes a crime out of things that are not crimes. A Prohibition law strikes a blow at the very principles upon which our government was founded." - Abraham Lincoln
"There are a thousand hacking at the branches of evil
to one who is striking at the root"
~ Henry D. Thoreau
Strike The Root
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Yrat]
#8556 - 04/22/08 01:58 PM (16 years, 7 months ago) |
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Your thinking of light reaction not dark reaction.
In dark reactions, carbon is broken away from carbon dioxide and combined with hydrogen via the Calvin cycle to create carbohydrates.
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Yrat
Happy Planting
Registered: 04/20/08
Posts: 886
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: erb]
#8562 - 04/22/08 02:10 PM (16 years, 7 months ago) |
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the light reaction is where light energy is converted to chemical energy in the forms of ATP and NADPH.
this chemical energy is then used in carbon fixation (part of the calvin cycle, or dark rxns), like you said, but carbon dioxide is never directly broken down to its constituents. it is combined with the 5-carbon sugar ribulose-1,5-bisphosphate.
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"Prohibition will work great injury to the cause of temperance. It is a species of intemperance within itself, for it goes beyond the bounds of reason in that it attempts to control a man's appetite by legislation, and makes a crime out of things that are not crimes. A Prohibition law strikes a blow at the very principles upon which our government was founded." - Abraham Lincoln
"There are a thousand hacking at the branches of evil
to one who is striking at the root"
~ Henry D. Thoreau
Strike The Root
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Yrat]
#8566 - 04/22/08 02:13 PM (16 years, 7 months ago) |
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yes it is..
carbon and oxygen from the Co2.
The carbon then combines with hydrogen to form carbs, via the Calvin cycle.
Edited by erb (04/22/08 02:24 PM)
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Yrat
Happy Planting
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Posts: 886
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: erb]
#8586 - 04/22/08 02:34 PM (16 years, 7 months ago) |
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a quick search will show you otherwise
WHOLE CO2 is added to ribulose 1,5-bisphosphate
oxygen is produced during photosynthesis from the photolysis of water. it does not come from the carbon dioxide.
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"Prohibition will work great injury to the cause of temperance. It is a species of intemperance within itself, for it goes beyond the bounds of reason in that it attempts to control a man's appetite by legislation, and makes a crime out of things that are not crimes. A Prohibition law strikes a blow at the very principles upon which our government was founded." - Abraham Lincoln
"There are a thousand hacking at the branches of evil
to one who is striking at the root"
~ Henry D. Thoreau
Strike The Root
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Yrat]
#8620 - 04/22/08 03:10 PM (16 years, 7 months ago) |
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Your still talking about the light reaction not dark reaction.
Notice how it says "carbon is broken away from CO2"
photosynthesis
The process by which green plants, algae, diatoms, and certain forms of bacteria make carbohydrates from carbon dioxide and water in the presence of chlorophyll, using energy captured from sunlight by chlorophyll, and releasing excess oxygen as a byproduct. In plants and algae, photosynthesis takes place in organelles called chloroplasts. Photosynthesis is usually viewed as a two-step process. First, in the light reactions, the energy-providing molecule ATP is synthesized using light energy absorbed by chlorophyll and accessory pigments such as carotenoids and phycobilins, and water is broken apart into oxygen and a hydrogen ion, with the electron of the hydrogen transferred to another energy molecule, NADPH. The ATP and NADPH molecules power the second part of photosynthesis by the transfer of electrons. In these light-independent or dark reactions, carbon is broken away from carbon dioxide and combined with hydrogen via the Calvin cycle to create carbohydrates. Some of the carbohydrates, the sugars, can then be transported around the organism for immediate use; others, the starches, can be stored for later use. Compare chemosynthesis. See Note at transpiration.
A Closer Look Almost all life on Earth depends on food made by organisms that can perform photosynthesis, such as green plants, algae, and cyanobacteria. These organisms make carbohydrates from carbon dioxide and water using light energy from the Sun. They capture this energy with various pigments which absorb different wavelengths of light. The most important pigment, chlorophyll a, captures mainly blue and red light frequencies, but reflects green light. In plants, the other pigments are chlorophyll b and carotenoids. The carotenoids are usually masked by the green color of chlorophyll, but in temperate environments they can be seen as the bright reds and yellows of autumn after the chlorophyll in the leaves has broken down. The energy gathered by these pigments is passed to chlorophyll a. During the light reactions, the plant uses this energy to break water molecules into oxygen (O2), hydrogen ions, and electrons. The light reactions produce more oxygen than is needed for cellular respiration, so it is released as waste. All of the oxygen in the Earth's atmosphere today was produced as waste by photosynthetic organisms, especially cyanobacteria, which have been producing oxygen for some three billion years, since their first appearance in the Precambrian Eon. During the dark reactions, the plant uses hydrogen ions and the electrons to make carbon dioxide into carbohydrates. Within the leaf of a green plant, photosynthesis takes place in chlorophyll-containing chloroplasts in the column like cells of the palisade layer and in the cells of the spongy parenchyma. The cells obtain carbon dioxide from air that enters the leaf through holes called stomata, which also allow excess oxygen to escape. Water from the roots is brought to the leaf by the vascular tissues called xylem, while the carbohydrates made by the leaf are distributed to the rest of the plant by the vascular tissue called phloem.
dark reaction
Any of the chemical reactions that take place during the second stage of photosynthesis and do not require light. During the dark reactions, energy released from ATP (created by the light reactions) drives the fixation of carbon from carbon dioxide in organic molecules. The Calvin cycle forms part of the dark reactions. As long as ATP is available, the dark reactions can occur in darkness or in light. Compare light reaction. See more at Calvin cyclephotosynthesis
Edited by erb (04/22/08 03:26 PM)
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CaptainKirk
Sailing the Seas of Cheese
Registered: 04/20/08
Posts: 41
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: erb]
#8645 - 04/22/08 03:25 PM (16 years, 7 months ago) |
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i didnt even bother with all that cut and paste jazz...cause the bottom line is 24 hr = faster growth IME
..18 works well too ..its really not that big an issue..18 is nice for the simple fact that your equipment can rest..which in summer is nice ..
i run 24  both are fine and work well
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: CaptainKirk]
#8654 - 04/22/08 03:30 PM (16 years, 7 months ago) |
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There is some good info from me in that first post, i wouldn't dismiss it as copy and paste jazz.
18 means less heat.
As far as the ballast and bulb go, its better for the longevity if you don't turn them on and off alot.
Edited by erb (04/22/08 03:56 PM)
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Yrat
Happy Planting
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Posts: 886
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: erb]
#8729 - 04/22/08 04:39 PM (16 years, 7 months ago) |
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dude, trust me. the cycles and reactions are forever scarred into my memory from years of biochemistry and botany. light rxn, dark rxn, it doesn't matter, carbon is NOT cleaved away from CO2.
here's a VERY dumbed down version I yoinked off the web in 3 seconds for you
notice that CO2 is added to the ribulose 1,5-bisphosphate to yield two 3-phosphoglycerates, also known as glycerate 3-phosphate.
balance the equations if you dont believe me.
i will scan the pages out of my old biochem texts if you would like.
the only reason i am pursuing this is because i've seen what happens when misinformation runs rampant at the shroomery, and don't want that stuff to start up here.
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"Prohibition will work great injury to the cause of temperance. It is a species of intemperance within itself, for it goes beyond the bounds of reason in that it attempts to control a man's appetite by legislation, and makes a crime out of things that are not crimes. A Prohibition law strikes a blow at the very principles upon which our government was founded." - Abraham Lincoln
"There are a thousand hacking at the branches of evil
to one who is striking at the root"
~ Henry D. Thoreau
Strike The Root
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Yrat
Happy Planting
Registered: 04/20/08
Posts: 886
Last seen: 10 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Yrat]
#8753 - 04/22/08 04:58 PM (16 years, 7 months ago) |
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Furthermore, all the protons (H+) generated in the light rxn from the splitting of water (2H2O -> 4H+ + O2) are used to generate a proton gradient across the thylakoid membrane. This gradient is used in an electron transfer system that ultimately generates ATP and NADPH (which then go on to fixate CO2 in the dark rxn). The protons generated in the light rxn do NOT go on to form carbohydrates.
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"Prohibition will work great injury to the cause of temperance. It is a species of intemperance within itself, for it goes beyond the bounds of reason in that it attempts to control a man's appetite by legislation, and makes a crime out of things that are not crimes. A Prohibition law strikes a blow at the very principles upon which our government was founded." - Abraham Lincoln
"There are a thousand hacking at the branches of evil
to one who is striking at the root"
~ Henry D. Thoreau
Strike The Root
Edited by Yrat (04/23/08 06:48 AM)
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Yrat]
#8911 - 04/22/08 05:57 PM (16 years, 7 months ago) |
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It's semantics..
You can say the c02 is reduced or the carbon is fixed to form carbohydrates, same difference.
Edited by erb (04/22/08 10:02 PM)
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Yrat
Happy Planting
Registered: 04/20/08
Posts: 886
Last seen: 10 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: erb]
#9005 - 04/22/08 06:45 PM (16 years, 7 months ago) |
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oxygen is released in the light rxn from the splitting of water and is not related to carbon dioxide
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"Prohibition will work great injury to the cause of temperance. It is a species of intemperance within itself, for it goes beyond the bounds of reason in that it attempts to control a man's appetite by legislation, and makes a crime out of things that are not crimes. A Prohibition law strikes a blow at the very principles upon which our government was founded." - Abraham Lincoln
"There are a thousand hacking at the branches of evil
to one who is striking at the root"
~ Henry D. Thoreau
Strike The Root
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Yrat]
#9343 - 04/22/08 08:39 PM (16 years, 7 months ago) |
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dill705
Turns Shrooms to Weed
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: erb]
#9560 - 04/22/08 09:58 PM (16 years, 7 months ago) |
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I appreciate this thread. I've always wondered this and now have some answers.
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It's funny how when you're talking about testing the first nuclear weapon, which some scientists thought could possibly set off a chain reaction that would burn off our entire atmosphere and leave a lifeless barren rock floating in space, the risk is justified. But if a few extra people might get stoned it's just too dangerous to try.
-FF
I got $50 on Barack!!!
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Sirius
Saturn Ascends
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: dill705]
#10108 - 04/23/08 02:30 AM (16 years, 7 months ago) |
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Yes, this thread is great. My friend is going with 24.
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