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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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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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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
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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
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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
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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
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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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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
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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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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
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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
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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
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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
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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
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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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erb
Registered: 04/20/08
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Sirius]
#45742 - 06/01/08 06:09 AM (16 years, 6 months ago) |
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Thanks!
To bad its cluttered with a bunch of crap.
Edited by erb (06/01/08 06:46 AM)
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Harry_Ba11sach
cannoisseur
Registered: 04/20/08
Posts: 11,753
Loc: Nepal 
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: erb]
#47797 - 06/01/08 11:11 AM (16 years, 6 months ago) |
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did you really just bump this thread to say that?
I find it especially humorous as you're the one who was wrong.
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erb
Registered: 04/20/08
Posts: 198
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Harry_Ba11sach]
#47800 - 06/01/08 11:14 AM (16 years, 6 months ago) |
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Your dense..no i wasnt.
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Harry_Ba11sach
cannoisseur
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: erb]
#47817 - 06/01/08 11:54 AM (16 years, 6 months ago) |
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I'm dense? Everything said by Yrat was correct, and instead of posting supporting information you simply continued to repeat the same tired phrase, which wasn't even correct.
Until you actually say something with some substance (and cite your source) you're the one who looks the fool.
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MFDoom666
trash hoarder
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Harry_Ba11sach]
#47845 - 06/01/08 01:06 PM (16 years, 6 months ago) |
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yrat pwned.
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FurrowedBrow said:
They should teach african engineering at the college level. mcgyver 101
Harry_Ba11sach said:
Has anyone really been far even as decided to use even go want to do look more like?
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m3kgt
User
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Harry_Ba11sach]
#48627 - 06/02/08 04:57 AM (16 years, 6 months ago) |
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Quote:
Harry_Ba11sach said:
Until you actually say something with some substance (and cite your source) you're the one who looks the fool.
The first post was partially pasted from some info thats been floating around other grow forums. rollitup and grasscity to be exact.
The second post about photosynthesis and dark periods is strait off http://www.thefreedictionary.com/photosynthesis
Not that its bad that you are passing on knowledge to other members but think twice to argue about a subject that someone has actually studied and is correcting you.
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erb
Registered: 04/20/08
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: m3kgt]
#48747 - 06/02/08 09:06 AM (16 years, 6 months ago) |
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i copied some of it from my others posts under the same screenname (erb) at rollitup as well as from other posts i have made on the subject.I did not plagiarize anyone.
some of the scientific info is not mine but gathered from other sources.
the second part on photosynthesis is of course not mine.
My point was, its really saying the same thing in two different ways, semantics.
I really wasnt trying to cause a big problem, just felt it was nitpicking.
peace
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Warpainted
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: erb]
#123048 - 09/16/08 03:06 PM (16 years, 3 months ago) |
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I'm not going to lie, I have no clue what the debate part of this thread was about.
So question: Does the plant use co2 during light, and oxygen during dark?
If you are doing 18/6, would it be better to adjust ppm lower about .5 hour before the 6 hour dark period to allow more oxygen during dark periods?
Then raise it when the lights come back on?
Is there any benefit, other than keeping roots colder, to the dark periods?
Thanks
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Yrat
Happy Planting
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Warpainted]
#123075 - 09/16/08 05:52 PM (16 years, 3 months ago) |
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the plants will always use oxygen, as oxygen is used to break down carbohydrates for energy, the same reason we need it. the plant is constantly growing and needing energy in both the dark and the light, so oxygen is taken in constantly. most CO2 is used mainly in the light, when there is photosynthetic energy to build carbohydrates from it (which will later be used as energy to grow). this process requires that energy from the light to work. As soon as it gets dark, the whole system really just shuts off after reserves of ATP and NADPH wind down.
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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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Magash
The Feminizer
Registered: 04/21/08
Posts: 6,634
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Yrat]
#123372 - 09/17/08 08:48 AM (16 years, 3 months ago) |
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Wanna know how to solve this problem? Two grow rooms the same strain in each. One under 24hrs one 18hrs.
Now myself I did this and like the reaction of 18/6. Then again this can also be strain related. There are strains like Mikado aka Sweet Pink Grapefruit that after a few months will start to flower even under the 18/6 but not under the 24hrs of light. This can be a real problem if you have a strain you don't wanna loose.
I love all the scientific talk and all but I'm a side by side and see for myself which works better kind of guy. Been doing it like that since 85 and it seems to be working.
   
  
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All creatures tremble when faced with violence. All creatures fear death, all love life. If we can only see ourselves in others, then how could we possibly hurt another creature?
 Join us at the Growery!
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Yrat
Happy Planting
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Magash]
#123411 - 09/17/08 09:30 AM (16 years, 3 months ago) |
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Quote:
Magash said:
I'm a side by side and see for myself which works better kind of guy.
me too, such experiments are the essence of the scientific method. there is no way to know which conditions are better other than doing a side-by-side with an unknown and a control.
that bogglegum is amazing. absolutely amazing.
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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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RustyShaklford
Registered: 09/22/08
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Sirius]
#125088 - 09/23/08 05:06 PM (16 years, 2 months ago) |
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The very first post in this thread was informative. . . As a newb, however, everything else might as well be said in some foreign language. I can't even remember 99% of the words used to describe,,,, something, without scrolling back up.
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DungenessDank
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: RustyShaklford]
#125113 - 09/23/08 07:26 PM (16 years, 2 months ago) |
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I tend to side with Yrat on this issue, seems like he knows what hes talking about.
Personally what do I think? I think 20/4 is as good as or better than 24/0. I think the 4 hours of darkness has to do it some good, even if just letting the equipment cool down.
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erb
Registered: 04/20/08
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: RustyShaklford]
#127355 - 10/01/08 07:27 AM (16 years, 2 months ago) |
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Quote:
RustyShaklford said:
The very first post in this thread was informative. . . As a newb, however, everything else might as well be said in some foreign language. I can't even remember 99% of the words used to describe,,,, something, without scrolling back up.
thank you!
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t0ad
ribbit ribbit
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Sirius]
#128088 - 10/02/08 03:50 PM (16 years, 2 months ago) |
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i've read that the stomata's on the underside of the leaves will automatically close after 18 hours, photosynthesis requires a light & dark period naturally. 18/6 FTW...
24hr period is just wasting electricity imho...
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<img src="/forums/images/graemlins/hypnotoad.gif" alt="" />
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Sirius
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: t0ad]
#128120 - 10/02/08 06:50 PM (16 years, 2 months ago) |
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Quote:
t0ad said:
i've read that the stomata's on the underside of the leaves will automatically close after 18 hours, photosynthesis requires a light & dark period naturally. 18/6 FTW...
If you have any source on that, it would be greatly appreciated...
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t0ad
ribbit ribbit
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Sirius]
#128130 - 10/02/08 07:16 PM (16 years, 2 months ago) |
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it was a botany text-book, it wasn't specific to Marijuana; but I have a firm belief in that. It's natural and it's science. I've never seen this "C4" "C3" plant types before. 
haven't seen any proof that 24/0 is any better; like several said before that it comes down to a controlled scientific experiment, using clones so that the exact same plant should grow as evenly, and closely as possible and the variable would be the lighting.
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<img src="/forums/images/graemlins/hypnotoad.gif" alt="" />
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t0ad
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: t0ad]
#128134 - 10/02/08 07:29 PM (16 years, 2 months ago) |
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this pic below may help others understand what the original post was talking about. . . but still a firm believer in plants need darkness. The Stomata's are what actually absorb energy for the plant; Naturally they open upon light sensation from darkness, though the plant doesn't require a dark period, when the stomatas close this causes the plant to submerse itself into a "dark period" - it causes itself to stop making energy and to use it. It's not the energizer bunny that can keep going and going... At one point, the plant stops making energy and uses what has been stored and does not require an absolute "lack of light/darkness" to close it's stomatas. They look like tiny mouths underneath the leaves. . . Which is why hacking off some of the bigger fan leaves to get more light to the lower end does not help the plant anymore than finding a way to redirect light which is less stressful on the plant.
Here's a C3 Plant cycle (was kidding about above reference)
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<img src="/forums/images/graemlins/hypnotoad.gif" alt="" />
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Yrat
Happy Planting
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: t0ad]
#128254 - 10/03/08 06:58 AM (16 years, 2 months ago) |
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Quote:
t0ad said:
The Stomata's are what actually absorb energy for the plant
the stomata do not absorb energy. chlorophyll allows plants to absorb energy from light. chlorophyll is contained in the thylakoid membranes of chloroplasts, which are subcellular organelles, while stomata are multicellular structures. they allow for gaseous exchange across the surface of the leaves. CO2 goes in, and O2 goes out, along with water vapor, the final destination for water drawn up through the roots. There are many reasons for the opening and closing of stomata, including lack of water, and it gets complicated when starting to examine C3 plants.
i like how your figure supports everything i have said earlier in this thread.
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Sirius
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: t0ad]
#128257 - 10/03/08 07:29 AM (16 years, 2 months ago) |
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Quote:
t0ad said:
Naturally they open upon light sensation from darkness, though the plant doesn't require a dark period, when the stomatas close this causes the plant to submerse itself into a "dark period" - it causes itself to stop making energy and to use it. It's not the energizer bunny that can keep going and going... At one point, the plant stops making energy and uses what has been stored and does not require an absolute "lack of light/darkness" to close it's stomatas.
The stomata also can open during when it is dark due to the fact that the guard cells have an internal clock that is used in the absence of light. However, I haven't seen anything that suggests the stomata actually close simply because they've had more than a certain amount of hours of light. I also haven't seen any evidence to suggest that plants aren't "energizer bunnies" that keep going, going, and going with the production of energy. As long as all the internal and external cues are in place, then it makes sense that they are going to remain open for transpiration and the absorption of CO2 to take place. I'm still looking for more information on this, but in the meantime, I'd love to be pointed in the direction of something that says otherwise.
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t0ad
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Sirius]
#128453 - 10/03/08 04:03 PM (16 years, 2 months ago) |
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yeah wikipedia had that neat little chart, so you could say I borrowed it from them.
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<img src="/forums/images/graemlins/hypnotoad.gif" alt="" />
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erb
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: t0ad]
#132661 - 10/15/08 09:35 AM (16 years, 2 months ago) |
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If anyone plans on doing a 18/6 - 24/0 comparison remember the other variables involved, heat and Co2.
There is no point in going 24/0 if your not supplying the the plant with enough Co2 and keeping your heat low enough to prevent stretching.
There are other variables that must be taken into account if you want to do a true scientific experiment.
Some people will see better growth with 18/6 for two simple reasons. One is less heat, two is the average Co2 level will be higher. if your not supplementing your Co2 or venting good enough, more hours of light wont make much of a difference, the rest of the plants needs must be met to take advantage the increase in light.
This also includes an increase in water and nutrient needs.
Complicated scientific terms are great if they can be understand and utilized, but that is not the case here, it's unnecessary and causes unneeded confusion for the majority of people.
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erb
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: erb]
#132682 - 10/15/08 11:12 AM (16 years, 2 months ago) |
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For those that are interested in the scientific aspect, I found this explanation of the Calvin cycle helpful.
The Calvin Cycle:
ATP and NADPH produced by the light reactions are used in the Calvin cycle to reduce carbon dioxide to sugar.
The Calvin cycle is similar to the Krebs cycle in that the starting material is regenerated by the end of the cycle.
Carbon enters the Calvin cycle and leaves as sugar.
ATP is the energy source, while NADPH is the reducing agent that adds high energy electrons to form sugar.
The Calvin cycle actually produces a 3 carbon sugar glyceraldehyde 3-phosphate.
The Calvin cycle may be divided into 3 steps.
Step 1: Carbon Fixation. This phase begins when a carbon dioxide molecule is attached to a 5 carbon sugar, ribulose biphosphate (RuBP).
This reaction is catalyzed by the enzyme RuBP carboxylase (rubisco) one of the most abundant proteins on earth.
The products of this reaction is an unstable 6 carbon compound that immediately splits into 2 molecules of 3-phosphoglycerate.
For every 3 molecules of carbon dioxide that enter the cycle via rubisco, 3 RuBP molecules are carboxylated forming 6 molecules of 3-phosphoglycerate.
Step 2: Reduction. This endergonic reduction phase is a 2 step process that couples ATP hydrolysis with the reduction of 3-phosphoglycerate to glyceraldehyde phosphate.
An enzyme phosphorylates ( adds a phosphate) 3-phosphoglycerate by transferring a phosphate from the ATP. The product is 1-3-bisphosphoglycerate.
Electrons from the NADPH reduce the carboxyl group of the 1-3-bisphosphoglycerate to the aldehyde group of glyceraldehyde-3-phosphate.
For every three carbon dioxide molecules that enter the Calvin cycle,6 glyceraldehyde-3-phosphates are produced, only one can be counted as a net gain. The other 5 are used to regenerate 3 molecules of RuBP.
Step 3: Regeneration of RuBP. A complex series of reactions rearranges the carbon skeletons of 5 glyceraldehyde-3-phosphate molecules into 3 RuBP molecules. These reactions require 3 ATP molecules.
RuBP is thus regenerated to begin the cycle again.
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Yrat
Happy Planting
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: erb]
#132724 - 10/15/08 12:37 PM (16 years, 2 months ago) |
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Quote:
erb said:
Step 1: Carbon Fixation. This phase begins when a carbon dioxide molecule is attached to a 5 carbon sugar, ribulose biphosphate (RuBP).
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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
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Yrat]
#132974 - 10/15/08 11:19 PM (16 years, 2 months ago) |
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There are several stages in the progress of the carbon dioxide. It boils down to vocabulary. Just like any chemical reaction you have the reactants and the products. Everything else is just fine tuning.
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BulkBread
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Sirius]
#219970 - 04/26/09 07:05 PM (15 years, 7 months ago) |
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Bump
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Harry_Ba11sach
cannoisseur
Registered: 04/20/08
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: BulkBread]
#219988 - 04/26/09 08:05 PM (15 years, 7 months ago) |
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ummm....why? please don't bump threads unless you actually have something productive to add to the conversation. This was pointless.
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therealziz
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Harry_Ba11sach]
#220008 - 04/26/09 08:33 PM (15 years, 7 months ago) |
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whats bumping?
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MFDoom666
trash hoarder
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: therealziz]
#220018 - 04/26/09 09:13 PM (15 years, 7 months ago) |
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bringing an old post back to life.
only retards do it.
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FurrowedBrow said:
They should teach african engineering at the college level. mcgyver 101
Harry_Ba11sach said:
Has anyone really been far even as decided to use even go want to do look more like?
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erb
Registered: 04/20/08
Posts: 198
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: MFDoom666]
#225587 - 05/12/09 02:32 PM (15 years, 7 months ago) |
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Harry_Ba11sach
cannoisseur
Registered: 04/20/08
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Loc: Nepal
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: erb]
#225590 - 05/12/09 02:35 PM (15 years, 7 months ago) |
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Oh hey look who it is, the guy who was really really wrong in this thread
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Yrat
Happy Planting
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: erb]
#225630 - 05/12/09 04:33 PM (15 years, 7 months ago) |
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nice plant
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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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