Maxx PPFD ?

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ThaiBaby1

Well-Known Member
Certain people are here only to troll, they have to be ignored one way or another. Plants don't really need to have overhead lighting if they are surrounded by side lighting. The advantage is that they don't strech upwards to the light.
 
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Shugglet

Well-Known Member
ThaiBaby1 said:
Certain people are here only to troll, they have to be ignored one way or another. Plants don't really need to have overhead lighting if they are surrounded by side lighting. The advantage is that they don't strech upwards to the light.
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Lets not forget hes scrogging as well. The plants still stretch toward the light though.

Typically, vertical growing is designed to more efficiently use the light being output in a given volume of space.

Ttys' setup doesnt really achieve this goal. It might use the volume more efficiently. MIGHT, but I have serious doubts about that too.

Its not that ttys setup is necessarily worse than a standard horizontal grow, its just that it doesnt appear to be any better either. Simply different.
 
BobCajun

BobCajun

Well-Known Member
MeGaKiLlErMaN said:
There is no fighting gravity... The plants adapt and the light isn't effected... The point is that you can yield more per sq/ft of space with vertical... Like 3 times as much or more depending on how close you want to get
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Okay but is it 3 times as much per watt or per floor space? Can't see getting 3 times as much per watt, though probably slightly more. It's the same amount of light, just spread in a circle around the bulb rather than reflected in a single downward direction. And the vertical growing just seems more troublesome to set up. I guess it's a personal choice. I have no interest in it myself.
 
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Shugglet

Well-Known Member
BobCajun said:
Okay but is it 3 times as much per watt or per floor space? Can't see getting 3 times as much per watt, though probably slightly more. It's the same amount of light, just spread in a circle around the bulb rather than reflected in a single downward direction. And the vertical growing just seems more troublesome to set up. I guess it's a personal choice. I have no interest in it myself.
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You could maybe yield 3x with the same watts, but that's with an omnidirectional light. using a directional light removes that advantage. this isn't rocket science...
 
MeGaKiLlErMaN

MeGaKiLlErMaN

Well-Known Member
BobCajun said:
Okay but is it 3 times as much per watt or per floor space? Can't see getting 3 times as much per watt, though probably slightly more. It's the same amount of light, just spread in a circle around the bulb rather than reflected in a single downward direction. And the vertical growing just seems more troublesome to set up. I guess it's a personal choice. I have no interest in it myself.
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If light is getting reflected and the reflective material is around 94-92% efficient... Doesn't seem like there will me much of a loss at all, so the theory of a bare bulb being that much better is pretty far fetched to me... It's per sq/ft never said per watt. That said COBs can be ran much closer and pushed on both sides...

Imagin a plant that's grown vertically, it's 6ft high by 5 ft wide, the less can be ran 12-6in off of the canopy and then you can have another plant right behind the passively cooled/water cooled LEDs... So if you had a room that was say 10x6x8... 1ft walk way and then you could fit 8 5x6s where you would normally get 1.5 ish... So this situation would net you 8x the yield on the same space.
 
BobCajun

BobCajun

Well-Known Member
MeGaKiLlErMaN said:
If light is getting reflected and the reflective material is around 94-92% efficient... Doesn't seem like there will me much of a loss at all, so the theory of a bare bulb being that much better is pretty far fetched to me... It's per sq/ft never said per watt. That said COBs can be ran much closer and pushed on both sides...

Imagin a plant that's grown vertically, it's 6ft high by 5 ft wide, the less can be ran 12-6in off of the canopy and then you can have another plant right behind the passively cooled/water cooled LEDs... So if you had a room that was say 10x6x8... 1ft walk way and then you could fit 8 5x6s where you would normally get 1.5 ish... So this situation would net you 8x the yield on the same space.
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Alright, anyway I think another thread in "Vertical Growing" would be more appropriate for this subject. Poor OP just asked what the max PPFD would be.
 
B

Budget Buds

Well-Known Member
BobCajun said:
Alright, anyway I think another thread in "Vertical Growing" would be more appropriate for this subject. Poor OP just asked what the max PPFD would be.
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Threads have a way of evolving , I got my info so it's all good :)
Hybridway said:
I haven't read through this yet to see if anybody actually answer you, but Cannabises light saturation point is 1750.
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I didnt get that exact answer but I got a range :)
 
Hybridway

Hybridway

Well-Known Member
Shugglet said:
Do these figures consider co2 supplementation or does that change things?
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Not sure.
Olive Drab Green said:
CO2 won't allow your plant to exceed 1500. You'll start to harm your plants. Stick to that and that's all you need to achieve to maximize your potential.
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Co2 allows for higher temps & is actually best absorbed around 90• but if you weigh out the pro's n cons, it's not worth it. I liked 80-85• w/ my HPS taking into consideration the leaf temp would be approx. 5-8• higher then room temp.
Since using good led though I've made changes to all that. Now I like 78-82• w/ led & Co2 between 900-1300.
You're pretty right on though. Over 1500 ppfd isn't good for all strains. Some can hack it but I doubt there's much benefit.
 
Uberknot

Uberknot

Well-Known Member
Hybridway said:
I haven't read through this yet to see if anybody actually answer you, but Cannabises light saturation point is 1750.
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I have seen this...some can take more than others 1750 seems to be a max for Savtiva's.

An inexpensive spectrophotometer can give you a decent estimate of your DLI. Some anecdotal evidence points to 25 mol-1m-2day-1 (25 moles of photons per square meter per day) as the “saturation point” for cannabis. After this saturation point is reached, the plant doesn’t require further light except to maintain its light schedule.

and this

http://link.springer.com/article/10.1007/s12298-008-0027-x

Effect of different photosynthetic photon flux densities (0, 500, 1000, 1500 and 2000 μmol m−2s−1), temperatures (20, 25, 30, 35 and 40 °C) and CO2 concentrations (250, 350, 450, 550, 650 and 750 μmol mol−1) on gas and water vapour exchange characteristics of Cannabis sativaL. were studied to determine the suitable and efficient environmental conditions for its indoor mass cultivation for pharmaceutical uses. The rate of photosynthesis (PN) and water use efficiency (WUE) of Cannabis sativa increased with photosynthetic photon flux densities (PPFD) at the lower temperatures (20–25 °C). At 30 °C, PN and WUE increased only up to 1500 μmol m−2s−1 PPFD and decreased at higher light levels. The maximum rate of photosynthesis (PN max) was observed at 30 °C and under 1500 μmol m−2s−1 PPFD. The rate of transpiration (E) responded positively to increased PPFD and temperature up to the highest levels tested (2000 μmol m−2s−1 and 40 °C). Similar to E, leaf stomatal conductance (gs) also increased with PPFD irrespective of temperature. However, gs increased with temperature up to 30 °C only. Temperature above 30 °C had an adverse effect on gs in this species. Overall, high temperature and high PPFD showed an adverse effect on PN and WUE. A continuous decrease in intercellular CO2 concentration (Ci) and therefore, in the ratio of intercellular CO2 to ambient CO2 concentration (Ci/Ca) was observed with the increase in temperature and PPFD. However, the decrease was less pronounced at light intensities above 1500 μmol m−2s−1. In view of these results, temperature and light optima for photosynthesis was concluded to be at 25–30 °C and ∼1500 μmol m−2s−1 respectively. Furthermore, plants were also exposed to different concentrations of CO2 (250, 350, 450, 550, 650 and 750 μmol mol−1) under optimum PPFD and temperature conditions to assess their photosynthetic response. Rate of photosynthesis, WUE and Ci decreased by 50 %, 53 % and 10 % respectively, and Ci/Ca, E and gs increased by 25 %, 7 % and 3 % respectively when measurements were made at 250 μmol mol-1 as compared to ambient CO2 (350 μmol mol−1) level. Elevated CO2 concentration (750 μmol mol−1) suppressed E and gs ∼ 29% and 42% respectively, and stimulated PN, WUE and Ci by 50 %, 111 % and 115 % respectively as compared to ambient CO2 concentration. The study reveals that this species can be efficiently cultivated in the range of 25 to 30 °C and ∼1500 μmol m−2s−1 PPFD. Furthermore, higher PN, WUE and nearly constant Ci/Ca ratio under elevated CO2 concentrations in C. sativa, reflects its potential for better survival, growth and productivity in drier and CO2 rich environment.
 
ttystikk

ttystikk

Well-Known Member
MeGaKiLlErMaN said:
If light is getting reflected and the reflective material is around 94-92% efficient... Doesn't seem like there will me much of a loss at all, so the theory of a bare bulb being that much better is pretty far fetched to me... It's per sq/ft never said per watt. That said COBs can be ran much closer and pushed on both sides...

Imagin a plant that's grown vertically, it's 6ft high by 5 ft wide, the less can be ran 12-6in off of the canopy and then you can have another plant right behind the passively cooled/water cooled LEDs... So if you had a room that was say 10x6x8... 1ft walk way and then you could fit 8 5x6s where you would normally get 1.5 ish... So this situation would net you 8x the yield on the same space.
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One foot walkway, lmao
 
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