The far red thread

[plebschmo]

2.1 umols will be relative to a certain wattage per diode. If you allready controlled for this, then yeah, youre right. Most people run too much eod far red, usually cause people was using mechanical timers with lowest time interval being 15 min. Random is sadly a bit MIA but im.familiar with his calculations.

Hey mate, thanks for your input!

I'm unsure as to the wattage which the PPF value is using. From https://www.cree.com/led-components/media/documents/XLampXPE2.pdf - it tells me temperature (Tj) is at 25 and the "calculated minimum flux" is 2.1 umol/s" - this says its "for reference only".

I'll be running the diodes at about their max (calculated how much I need to turn the current pot on a HLG-40H-30A) which according to the above info sheet is 2.15V x 1amp so about 2.15 watts each so 25.8W total for all 12.

Unfortunately the data sheet seems to be silent (or at least I cant find it) where it says how many W the diodes are running at when its giving me the "calculated minimum flux" of 2.1 umol/s...

Is there another way I can calculate how much PPF my bar will emit?


edit: So i just tested my end of day setup and my far red turns on 1 min before lights off and then 2 mins after lights off. Thinking of increasing this to 1 min before, 4 mins after just to be safe. What do u guys think?

 

[Barristan Whitebeard]

Hey mate, thanks for your input!

I'm unsure as to the wattage which the PPF value is using. From https://www.cree.com/led-components/media/documents/XLampXPE2.pdf - it tells me temperature (Tj) is at 25 and the "calculated minimum flux" is 2.1 umol/s" - this says its "for reference only".

I'll be running the diodes at about their max (calculated how much I need to turn the current pot on a HLG-40H-30A) which according to the above info sheet is 2.15V x 1amp so about 2.15 watts each so 25.8W total for all 12.

Unfortunately the data sheet seems to be silent (or at least I cant find it) where it says how many W the diodes are running at when its giving me the "calculated minimum flux" of 2.1 umol/s...

Is there another way I can calculate how much PPF my bar will emit?

Following the datasheet for the XP-E2 far red (Group 27), a photon flux of 2.1 μmol/second is calculated at 350mA.

Looking at the electrical characteristics graph (junction temperature of 25 °C) a couple pages forward, the voltage looks to be about 1.85 volts at 350mA. That would mean that each diode is running at .6475 watts.

Where did you buy your strips? Cutter Electronics?

 

[ChrispyCritter]

Timber and @RainDan made my 730nm light bar a few years ago. He's in the know about about it and will make what you want. I'm very happy with mine.
That's great info to know about how to calculate time on at lights out relative to the power of your lights. I run 10 minutes at lights out, and I thought the light intensity was not as important because it's just a signal trigger to put the plants to sleep. I need to learn more clearly.

 

[plebschmo]

Looking at the electrical characteristics graph (junction temperature of 25 °C) a couple pages forward, the voltage looks to be about 1.85 volts at 350mA. That would mean that each diode is running at .6475 watts.

Hey mate thanks for your help but I've set the driver to output about 1 amp. It's a HLG-40H-30A which is adjustable between 0.8 ~ 1.34A. I could wind it all the way down to .8A but I don't have anything to run the lights at 350mA.

However, looking at the data sheet more thoroughly I've found that relative flux vs current for far red increases by 260% at about 1A. Do flux and ppf increase linearly? I'm assuming they would considering this LED only produces a limited wave length.

With that in mind if I increase the photon flux by 260% (because my LEDs are running at close to 1A) I get 5.46 umol/second per LED so 65.62 umol/s from all the LEDs.

That means to get 4000 umol I would need to run the LEDs for 61 seconds. Surely this can't be right, it seems way to short of a time...

 

[Rocket Soul]

Hey mate thanks for your help but I've set the driver to output about 1 amp. It's a HLG-40H-30A which is adjustable between 0.8 ~ 1.34A. I could wind it all the way down to .8A but I don't have anything to run the lights at 350mA.

However, looking at the data sheet more thoroughly I've found that relative flux vs current for far red increases by 260% at about 1A. Do flux and ppf increase linearly? I'm assuming they would considering this LED only produces a limited wave length.

With that in mind if I increase the photon flux by 260% (because my LEDs are running at close to 1A) I get 5.46 umol/second per LED so 65.62 umol/s from all the LEDs.

That means to get 4000 umol I would need to run the LEDs for 61 seconds. Surely this can't be right, it seems way to short of a time...

Why do you think youre maths are off? You seem completely competent with numbers. Remember that the previous advice are all old, tech has gotten way more efficient and you can run timers in a different way. If you dont teust your maths do this: set them for 5 mins a for a week and see what happens. You will likely get stretch. Youre not considering that youre doing many watts and diodes here. Id go for one or two.mins. youre doing it right man, relax.

 

[joejack51]

Hey! After reading those 99 pages I decided to get some Far Red Led from Rapidled and build my own EoD system
Here is my set up:
I got 2 Flowering Tent size 2'x2'x4', I plan to put 6 Far Red in each tent (12 total on the same string) connected on the Meanwell LPC-35-700 Driver
My question is how long should I run those at light off?
I know that my space is 0,371612 Square meter and those Led are Minimum PPF : 2.2 μmol/s, I saw in this thread some of you were having a math formula for this, since my first language is not english I have a hard time figure this out by myself, can someone help me figure this out?
@Randomblame @Rocket Soul @anyone

 

[Rocket Soul]

Watts x (ppf/w) x time in seconds/ space in m2 = 3000-4000.

You need to calculate your watts next, voltage x current.

 

[joejack51]

Watts x (ppf/w) x time in seconds/ space in m2 = 3000-4000.

You need to calculate your watts next, voltage x current.

First, ty for taking the time to answer my question!
Not trying to be a deadweight or so but tbh im totally lost in this calculation
1. For the wattage calculation, Do I take the voltage mentionned in the product description: (Forward Voltage (@1000mA) : 2.24V) or do I have to convert it back first to 0.700mA since the driver I use is 0.700mA??? And for the calculation do I take the total wattage of the 6 led in the tent X by the PPF/w?
2. For the PPF/w, is it the 2.2 μmol/s divided by the total wattage of the 6 Led in the tent?
3. Time in sec is for the time the FR are on right? and this number is to be divided by my space in square meter (0,37)
I know some of those question are dumb but I prefer to ask dumb question and be 100% sure im right before putting this in application
@Rocket Soul again ty for your time!

 

[joejack51]

I think I figured it...
Step 1: Each led are 2.24v that will be run on 0.700mA, so 2.24 X 0.700 = 1.568 watt
Step 2: I got 6 of them in the tent, so 1.568 X 6 = 9.408 watt
Step 3: Result X PPF for those leds PPF is 2.2, so 9.408 X 2.2 = 20,6976
Step 4: Result X time in sec lets say 1min (60), so 20.6976 X 60 = 1241.856
Step 5: Result DIVIDED by space in square meter (0.37), so 1241.856 / 0.37 = 3356 (and some decimal)
So with only one minute at light off I get in the 3356 range
@Rocket Soul does it make sense to you???

 

[Rocket Soul]

I think I figured it...
Step 1: Each led are 2.24v that will be run on 0.700mA, so 2.24 X 0.700 = 1.568 watt
Step 2: I got 6 of them in the tent, so 1.568 X 6 = 9.408 watt
Step 3: Result X PPF for those leds PPF is 2.2, so 9.408 X 2.2 = 20,6976
Step 4: Result X time in sec lets say 1min (60), so 20.6976 X 60 = 1241.856
Step 5: Result DIVIDED by space in square meter (0.37), so 1241.856 / 0.37 = 3356 (and some decimal)
So with only one minute at light off I get in the 3356 range
@Rocket Soul does it make sense to you???

That looks fully correct

 

[Moflow]

...3000-4000 ...que?

So with only one minute at light off I get in the 3356 range ...3356 range?...

...maybe im lost or missing something too...bad day for maths to me....que resaca...

Saludos

He he he.....

 

[Rocket Soul]

...3000-4000 ...que? ...total ppf de la lampara me imagino...

So with only one minute at light off I get in the 3356 range ...3356 range?...

...maybe im lost or missing something too...bad day for maths to me....que resaca...

PD...@Moflow con la resaca de hoy (ayer los vecinos nos regalaron un garrafon de vino de su finca del norte y esta rico rico) no te pillo ni tu humor...estoy espeso...como te va?...

Saludos

3000-4000/m2 ppf in total to turn the plant into sleep mode. Our poster has 9.4w of 2.2 ppf/w
efficient leds: about 1200 ppf in 60 seconds and the space is 0.37m2.

 

[salmonetin]

thanks Bro RS...Then...

Total PPFD (umols/s/sm2) (To Turn the Plant Into Sleep Mode... in the Elected Time... in the Grow Space...)

Total PPFD (umols/s/sm2) = (Total Watts = Nº Leds x Voltage x Current) x (PPF/W of Leds) x (Elected Time) (in Seconds) / (Grow Space) (in m2)

Total PPFD (To Turn the Plant Into Sleep Mode) = (Nº LEDS x V x A) x (PPF/W) x (XX Sec) / (XX m2) = XX umols/s/sm2

...por tu like Bro RS añado mas info...

From Solarimeter to DLI from the Sun -
J/cm² to mol/dm² Conversion:
DLI from the Sun = ((measured J/cm²)/100) x 2.15 x Glass Transmittance %

What the Plants receive extra from the Grow Lights can also be Calculated –
therefore you Convert your PPFD Light Level to DLI with the Numbers of Lighted Hours

From PPFD to DLI Conversion –
μmol/sm² to mol/dm² Conversion:
DLI from the Grow Lights = (Hours x PPFD x3600)/1.000.000

Horticulture Grow Light Conversion Tools

MechaTronix - Grow light conversion tools W/m² - J/cm² - Lux - µmol/sm² - mol/dm²

Light conversion from solar radiation W/m² and daily radiation J/cm² to the new grow light standard PPFD µmol/sm² and daily light sum DLI mol/m². Easy conversion from old grow light values lux to PPFD µmol/sm² for sunlight, HPS SON-T and Metal halide grow lamps. Greenhouse light calculator...

www.horti-growlight.com

Saludos desde Tenerife

 

[SpideyManDan]

So is there any actual research into using far reds for initiating flower? Im really curious of what mixing spectrums could do for photosynthesis, but im trying to stay away from the broscience. I know that far reds can be mixed with other wavelengths in order to illicit the Emerson effect but im still trying to figure out in what ratio would they be optimal.

My main question is whether we have any scientific research into all of this or is it just marketing from companies?

 

[Kassiopeija]

My main question is whether we have any scientific research into all of this

Yes, the mechanisms of the Phytochromes is known, and that plants can also photosynthetically harvest light "beyond the red drop" up to 780nm. It is not possible to overstimulate Photosystem I - because superfluous energy is used up in the "cyclical electron transport". Usually Photosystem II is overactive as it's Light-Harvesting Complex is twice as large as LHC I. Therefore Bugbee et al pointed out, that the boost to 730nm light resulted in an extraordinairly boost in growth - if combined with a fullspectrum/white light.
But beware: 730nm should never be higher than 660nm during the daytime.

 

[SpideyManDan]

Yes, the mechanisms of the Phytochromes is known, and that plants can also photosynthetically harvest light "beyond the red drop" up to 780nm. It is not possible to overstimulate Photosystem I - because superfluous energy is used up in the "cyclical electron transport". Usually Photosystem II is overactive as it's Light-Harvesting Complex is twice as large as LHC I. Therefore Bugbee et al pointed out, that the boost to 730nm light resulted in an extraordinairly boost in growth - if combined with a fullspectrum/white light.
But beware: 730nm should never be higher than 660nm during the daytime.

Yeah ive seen the things that Bruce was talking about on "far red: the forgotten photon" and its involvement in photosynthesis, but i was more referring to the whole flower initiating thing i saw a while back and if it has any veracity. Im not too sure if there is any research out there hinting that you can put a cannabis into flower earlier by using far red right before and after lights just come on.

Edit: BTW thank you for the reading material. Im going to save those and read up on it.

 

[Dr. Walter Bishop]

Are 2 boards of 20 Cree XP-E2 lights (Approximately 23 watts each strip) enough watt coverage to provide Emerson Effect for a 2X7 foot grow area?

I thinking of getting 2 of these...

Kingbrite Bar Kb20 Xp-e2 730nm Far Red Led Grow Booster Strip Light Include Mw Driver - Buy Led Bar,Kingbrite,Led Grow Light Product on Alibaba.com

Kingbrite Bar Kb20 Xp-e2 730nm Far Red Led Grow Booster Strip Light Include Mw Driver - Buy Led Bar,Kingbrite,Led Grow Light Product on Alibaba.com

www.alibaba.com

(for 2...Cost $150 delivered )

Thanks!

 

[SpideyManDan]

So I'm wondering if someone can help and give some advice. If we know far red is really important for photosynthesis then why do some high end lights not have any added 730?

I'm doing some research and getting info together and noticed that some leds, particularly the higher end diy kits, have no far red what so ever. Does that have a big effect on end results?

 

[PJ Diaz]

So I'm wondering if someone can help and give some advice. If we know far red is really important for photosynthesis then why do some high end lights not have any added 730?

I'm doing some research and getting info together and noticed that some leds, particularly the higher end diy kits, have no far red what so ever. Does that have a big effect on end results?

A lot of growers don't want the far red on during the entire duration of lights on, as it can cause excessive stretch in some strains.

 

[Kassiopeija]

So I'm wondering if someone can help and give some advice. If we know far red is really important for photosynthesis then why do some high end lights not have any added 730?

The understanding of Far Red photons is still not complete, and how plants capture this light has been an enigma since just a couple of years.

Then most white light diodes were/are created for human vision, so they do exclude some wavelengths because our eyes can't see them anyway, but plants can make readily use of it. These rays hold a potential to increase biomass and help in ripening.

However, as PJ stated, it can cause unwanted stretching, although Far Red itself is plenty in the suns natural spectrum, but indoor light does not fully mimic the sun's ratios, yet. So it stands to reason to have FR on a separate channel, then it could also be used for sleep initiation.