Various interesting links about lighting.

[DavidCampen]

http://ag.arizona.edu/ceac/sites/ag....20Lighting.pdf
The most interesting part of this paper is at the bottom of page 5, box on left titled: "End-of-day FR Light Treatment for Cucurbit Seedlings Grown under Artificial Lighting"

Only 30 minutes per day of far red (>700 nm) produced a significant increase in size. I have been think of adding far red lighting to my solarium to use end-of-day far red lighting to produce artificially long nights.

---------- Post added at 08:46 AM ---------- Previous post was at 08:31 AM ----------

http://www.lighting.philips.com/pwc_..._module-en.pdf

Philips is a large lighting and LED manufacturer. This data sheet is interesting in that it gives photon flux for their LED modules in micromoles of photons per second.

I wish that I could find some values of photon flux for linear fluorescent lamps given in micromoles per second.

Philips claims that their LED modules reduce energy consumption "up to 60%" compared to T8 linear fluorescent lamps. That would make their LED modules up 2.5 times as effective as T8 fluorescent, so 100 watts of fluorescent lighting could be replaced with as little as 40 watts of the Philips LED modules. To get this 2.5 times as effective figure you would have to be using their Deep Red only modules; notice that the photon flux for Deep Red modules is 1.79 micromoles per watt-second while for mixed Deep Red/Blue it is 1.56 micromoles per watt-second.

---------- Post added at 08:54 AM ---------- Previous post was at 08:46 AM ----------

http://amebse.nchu.edu.tw/documents/...on%20model.pdf

This paper gives photon flux densities in a growth chamber using fluorescent lamps but this paper is not interested in lighting efficiency; the lamps do not seem to have any reflector.

[Phal grower]

It couldn't hurt but at this point incandescent seems the only option for far red.

[DavidCampen]

Photoperiodism

This talks about how far red light at 730 nm can be used to produce an artificially long night.

There are far red LEDs. Here is the data sheet for a 10 watt LED module that emits at 740 nm.
http://www.ledengin.com/files/produc...LZ4-00R300.pdf

I use their 660 nm deep red modules in the LED lights that I have built.
http://www.ledengin.com/files/produc...LZ4-00R300.pdf

[zxyqu]

Interesting post David. Checking through it now. Do you have any thoughts on why Far Red spectra might be a plus? I figure late in the day when the sun is setting, that far red might be more prevalent, thus it's addition near day's end might better match "natural" lighting? Why do you say it may induce artificially long nights?

I see you've attached a new link while I was writing my response... Already ahead of me

[Phal grower]

I see, my interest is in far red producing larger leaves/plants. Let us know if you experiment with this and how it goes.

[DavidCampen]

Sunlight converts a plant pigment from one form, called Phytochrome-R (because its peak absorption is at 660 nm) to Phytochrome-FR (with a peak absorption at 730 nm). During the night, the Phytochrome-FR slowly converts back to Phytochrome-R but light at 730 nm will rapidly convert Phytochrome-FR to Phytochrome-R. It is believed that the night time conversion of Phytochrome-FR to Phytochrome-R is how daylength sensitive plants determine daylength.

---------- Post added at 10:08 AM ---------- Previous post was at 09:12 AM ----------

Originally Posted by DavidCampen

http://www.lighting.philips.com/pwc_..._module-en.pdf

Philips is a large lighting and LED manufacturer. This data sheet is interesting in that it gives photon flux for their LED modules in micromoles of photons per second.
...
Philips claims that their LED modules reduce energy consumption "up to 60%" compared to T8 linear fluorescent lamps. That would make their LED modules up 2.5 times as effective as T8 fluorescent, so 100 watts of fluorescent lighting could be replaced with as little as 40 watts of the Philips LED modules. To get this 2.5 times as effective figure you would have to be using their Deep Red only modules; notice that the photon flux for Deep Red modules is 1.79 micromoles per watt-second while for mixed Deep Red/Blue it is 1.56 micromoles per watt-second

The Philips datasheet does not say how the efficiency of these modules was measured. The efficiency of an LED decreases severely with increasing temperature. At 100 deg. C the efficiency of an LED may be only 60% of what it was at 20 deg. C. So if Philips measured the photon flux of these LED modules immediately after they were powered on and before the fixture had reached operating temperature then the stated efficiency would be unrealistically high. The stated efficiency of 2.5 times that of T8 fluorescent might really only be 1.5 at operating temperature.

[DavidCampen]

Originally Posted by DavidCampen

http://www.lighting.philips.com/pwc_..._module-en.pdf

Philips is a large lighting and LED manufacturer. This data sheet is interesting in that it gives photon flux for their LED modules in micromoles of photons per second.

I wish that I could find some values of photon flux for linear fluorescent lamps given in micromoles per second.

Philips claims that their LED modules reduce energy consumption "up to 60%" compared to T8 linear fluorescent lamps. That would make their LED modules up 2.5 times as effective as T8 fluorescent, so 100 watts of fluorescent lighting could be replaced with as little as 40 watts of the Philips LED modules. To get this 2.5 times as effective figure you would have to be using their Deep Red only modules; notice that the photon flux for Deep Red modules is 1.79 micromoles per watt-second while for mixed Deep Red/Blue it is 1.56 micromoles per watt-second .

Here is another datasheet from Philips for their HPS lamps. They give photosynthetic photon flux values for these lamps of 1.8-2.0 micromoles per watt-second. So these lamps are just as efficient as their LED modules.
On page 20 of this datasheet they give PPF values of 1.2 for their fluorescent lamps.
http://www.lighting.philips.com/pwc_...its-hid-en.pdf

So, using Philips data we have these PPF (micromoles per watt-second) values for different light sources:
1.2 - Fluorescent
1.8 - Deep Red LED
1.9 - HPS

By these figures, 80 watts (input power) of Deep Red LED lighting is equivalent to 120 watts (input power) of fluorescent lighting. So the LED lighting would use 1/3 less power than the equivalent fluorescent lighting.

[DavidCampen]

Another data point comparing photon flux from HPS and fluorescent light:
Comparison of fluorescent and high-pressure sodi... [HortScience. 1987] - PubMed - NCBI
"Radiation from high-pressure sodium (HPS) lamps ... compared to ... cool-white fluorescent (CWF) lamps at equal photosynthetic photon flux; ... input wattage was approximately 36% less. "

So by this data if a fluorescent lamp was providing 1.2 micromoles per watt-second then an HPS lamp would provide 1.9 micromoles per watt-second. This is in good agreement with the Philips data posted above.

For another data point we can look at a datasheet for a 10 watt, 660 nm (deep red) LED module:
http://www.ledengin.com/files/produc...LZ4-00R200.pdf
Typical operating parameters are given on page 4:
At an input current of 700 ma the forward voltage is 10.5 volts and the radiant flux is 2.2 watts. 700 ma times 10.5 volts gives an input power of 7.35 watts.

At an input current of 1000 ma the forward voltage is 11.4 volts and the radiant flux is 2.8 watts. 1000 ma times 11.4 volts gives an input power of 11.4 watts.

I calculate the energy content of photons at 660 nm to be 5.6 micromole per watt-second.

So for the LED operating at a current of 700 ma we have a photon flux of 2.2/7.35*5.6 micromoles per watt-second = 1.7 micromoles per watt-second. At an operating current of 1000 ma we get 1.4 micromoles per watt-second.

[isurus79]

Ok, just to start, I have to admit that this post is so far above my head that it might as well be written in Greek!

David, in your first post you mentioned that,

"Only 30 minutes per day of far red (>700 nm) produced a significant increase in size,"

so correct me if I'm wrong, but you are seeking to add far red lighting for 30 minutes per day to increase the size of your plant. Do you think its preferable to have one intense burst of red light at the beginning/end of the day (as in nature) or as a smaller dosage throughout the day? Would it be more efficient to have a few small red LED's strategically placed throughout your grow space that are on through the day or is it better to have lots of lights on for 30 minutes? I ask because I have recently purchased Ray's LED lights that plug into incandescent sockets. They have two small strips of red LEDs with a lot white ones. My guess is that the designer of these bulbs is banking on the importance red light in a small dosage through the day rather than one large dose. I have noticed that my small Stapelia variegata (cactus) has turned a really nice, healthy looking light purple color on the upper surface and I'm curious if this is due to the red lights in the LED. This plant has continued to grow during the winter, even though I understand they are normally supposed to be dormant during winter. I assume the growth is due to the warm temps afforded by indoor care.

I will be buying more of Ray's LEDs in the coming weeks/months as my indoor collection expands and I'm seeking to expand my VERY basic knowledge of the effects of lighting on my plants.

Finally, why did Philips compare their LED systems to T8 bulbs which are old technology and are less efficient than T5s? To me it seems that Philips is trying to bolster their product against a technologically less advanced version of the same product (ie. T8 vs. T5 bulb technology). Am I off base with this assumption?

[Ordphien]

Originally Posted by isurus79

Ok, just to start, I have to admit that this post is so far above my head that it might as well be written in Greek!

David, in your first post you mentioned that,

"Only 30 minutes per day of far red (>700 nm) produced a significant increase in size,"

so correct me if I'm wrong, but you are seeking to add far red lighting for 30 minutes per day to increase the size of your plant. Do you think its preferable to have one intense burst of red light at the beginning/end of the day (as in nature) or as a smaller dosage throughout the day? Would it be more efficient to have a few small red LED's strategically placed throughout your grow space that are on through the day or is it better to have lots of lights on for 30 minutes? I ask because I have recently purchased Ray's LED lights that plug into incandescent sockets. They have two small strips of red LEDs with a lot white ones. My guess is that the designer of these bulbs is banking on the importance red light in a small dosage through the day rather than one large dose. I have noticed that my small Stapelia variegata (cactus) has turned a really nice, healthy looking light purple color on the upper surface and I'm curious if this is due to the red lights in the LED. This plant has continued to grow during the winter, even though I understand they are normally supposed to be dormant during winter. I assume the growth is due to the warm temps afforded by indoor care.

I will be buying more of Ray's LEDs in the coming weeks/months as my indoor collection expands and I'm seeking to expand my VERY basic knowledge of the effects of lighting on my plants.

Finally, why did Philips compare their LED systems to T8 bulbs which are old technology and are less efficient than T5s? To me it seems that Philips is trying to bolster their product against a technologically less advanced version of the same product (ie. T8 vs. T5 bulb technology). Am I off base with this assumption?

I can understand more Greek than what's written in this thread.

I vaguely grasped about half of it... which I guess means I'm learning