# Arteficial light: few interesting datas



## dodidoki (Feb 22, 2013)

I use Osram Fluora T8 tubes for orchids, useful spectrum is about 70 % of full emitted light for plants, however useful ratio for plants of sunlight is about 10 % of full continous spectrum.

I measured light with light meter:

Osram Fluora T8 tubes, mirror -reflex armature ( without natural light):

4 tubes / 30 cm distance: 2200 lux.

4 tubes/ 50 cm distance: 1600 lux. 

2 tubes / 50 cm distence: 1100 lux.

Converted it to full sunlight:

- 2200x7= 15400 lux

-1600x7=11200 lux

-1100x7=7700 lux


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## dodidoki (Feb 22, 2013)

Another data:

light emission of tubes falls to 75% with comparison of new ones.


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## Ozpaph (Feb 22, 2013)

thanks.
why multiply by 7?


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## dodidoki (Feb 22, 2013)

These Fluora tubes have special spectral emission: there are two spikes at 440 nm and 660 nm. These two spikes are about 70% of total energy what these tubes produce.
Sunlight has a continous spectral emission, there are no special spikes in its spectral distribution. Maximal absorbtion of chlorophylles drops very steep within +/-7-8 nm from 440 and 660 nm so useful range of sunlight is only about 2x15 nm. Total visible spectrum starts at 400 and ends at 700, so useful part of visible light is only about 10 %( of sunlight).

10 % (sun) vs. 70% (Fluora)

So if you measure Fluora light it is 7x more intense than sunlight in useful range for plants.


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## dodidoki (Feb 22, 2013)

Fluora tube spectral distribution / chlorophyll absorbtion spectrum


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## dodidoki (Feb 22, 2013)

Sunlight spectral distribution
( these pics tell everything)


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## Rick (Feb 22, 2013)

I would argue that light quality and spectral charts does not reflect light intensity (strength) at any given wave lenght. (i.e.quality versus quantity)

So if you have 2000 lux and 70% of that is peak for photosynthesis, then you have 1400 lux of usefull light.

Sunlight on the other hand is much stronger than 2000 lux. A typical overcast day can have 10,000 to 25,000 lux and a sunny day is over 100,000 lux. So even if only 10% is in usable frequency as far as photosynthesis goes, overcast days would supply 1000 to 2500 lux, and sunny days 10,000 lux of prime photosynthetic light frequency.

So your 4 T8 bulb system at 30cm provides equivalent photosynthetic sunlight to being a plant outside on a cloudy day.


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## dodidoki (Feb 23, 2013)

Yes, you are right. I wrote these datas because if that is true, arteficial light with tubes are not enough for catts and phrags, but maybe enough for some paph.species.


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## Ray (Feb 23, 2013)

Rick beat me to it, but I'll add that you have to take the power, distance, and time into the thinking, as well.

An HPS bulb puts put almost no blue light, but by boosting the input power to 400 or 1000 watts, the little blue peak becomes a lot taller, making it acceptable for growth.

Likewise, a fluorescent lamp may not have a lot of illuminating output, but if you bring it close to the plants, the illumination-per-area is high enough to make it acceptable.

Then there is time of exposure. A slightly-reduced light intensity can be compensated for by increasing the "on" time for the lights.


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## TyroneGenade (Feb 23, 2013)

You should be measuring photons per square meter per second (PAR/m2 or Photosynthetically Photo Dynamic Flux). If you go have a look at http://www.apsa.co.za/board/index.php?topic=4454.0 you will see that the Osram Flora tube has 79.8% the PPFD of natural sunlight for the same wattage but only 54.7% the irradiance. But when you discuss light it isn't so simple as comparing measures such as this. You have to take into light distribution etc... If your 4 tubes were side by side then by moving them apart will change the Lux values a lot. If you have good quality reflectors then you can increase the Lux as you move the tubes further apart but only for a time, whereafter they will decrease. The further from the light source and the lux will drop again... but I digress.

If you are interested in growing plants under light the key issue is how much PPFD are the plants receiving. To emulate natural (indirect) sunlight (about 20 000 lux) you would need at least 350-370 PPFD.

There is a handy list of conversion factors at http://www.apogeeinstruments.co.uk/conversion-ppf-to-lux/


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## Rick (Feb 23, 2013)

Ray said:


> Then there is time of exposure. A slightly-reduced light intensity can be compensated for by increasing the "on" time for the lights.



This can make a big difference in the equation that I didn't suggest earlier.

In the real world the amount of sunlight is gradual from sunup til sundown, but with light bulbs its full on from On time to Off time.

The equivalent intensity of your bulbs maybe the same as for "noontime" on a cloudy day, but achieved for the full On time for your bulbs (probably 12-16 hours).

So you could achieve " equal or more" light with bulbs in comparison to cloudy sunlight conditions over the coarse of a 12-16 hour day.

Because the amount of cloud cover, day length, incident angle, understory shading,.......variables that go into figuring out plant light requirements on a long term basis are so extensive (and plants seem to grow just fine), I prioritize lighting issues fairly low these days. Unlike feeding issues, I've moved lighting into that category of finding "what works for that plant at this time" attitude.


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## dodidoki (Feb 23, 2013)

TyroneGenade said:


> You should be measuring photons per square meter per second (PAR/m2 or Photosynthetically Photo Dynamic Flux). If you go have a look at http://www.apsa.co.za/board/index.php?topic=4454.0 you will see that the Osram Flora tube has 79.8% the PPFD of natural sunlight for the same wattage but only 54.7% the irradiance. But when you discuss light it isn't so simple as comparing measures such as this. You have to take into light distribution etc... If your 4 tubes were side by side then by moving them apart will change the Lux values a lot. If you have good quality reflectors then you can increase the Lux as you move the tubes further apart but only for a time, whereafter they will decrease. The further from the light source and the lux will drop again... but I digress.
> 
> If you are interested in growing plants under light the key issue is how much PPFD are the plants receiving. To emulate natural (indirect) sunlight (about 20 000 lux) you would need at least 350-370 PPFD.
> 
> There is a handy list of conversion factors at http://www.apogeeinstruments.co.uk/conversion-ppf-to-lux/




Ohhh, it is too complicated to me! I think Fluora T8 has enough light energy for in low to medium light growing plants but in case of in higher light growing species, eg. catts, cymbidiums Fluora tubes have not enough energy in useful range. ( according to my measurment).
Question is more complicated, because I look after my ligh measuring device (ms 1300) and maesuring sensitivity distribution is not linear, similar to natural sunlight ( see diagram above), device has more sensitivity at green ( 500 nm) and less at around 400 and 600 nm. 
If I see sentsitivity diagramm compared with Fluora spectral diagram, measuring light energy under fluora will show about 60% of value light energy because of selective spectral sensitivity of device ( it measures mainly green peak of Fluora specrum and not 440 and 660 peak- energy)

Eg.: if I measure 2000 lux , it shows about 80% green light energy and 20 % useful energy. So useful energy is about 3200 lux.


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## Rick (Feb 23, 2013)

dodidoki said:


> Eg.: if I measure 2000 lux , it shows about 80% green light energy and 20 % useful energy. So useful energy is about 3200 lux.



You're meter should show total light output lux (all spectra). So you cannot get more energy for individual spectrum than the total output of the bulb. Your useful amounts are a fraction of the total (not more than the total).


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## dodidoki (Feb 23, 2013)

Rick said:


> You're meter should show total light output lux (all spectra). So you cannot get more energy for individual spectrum than the total output of the bulb. Your useful amounts are a fraction of the total (not more than the total).



Light meter sensitivity is calibrated for sunlight energy distribution. As you look at sunlight spectrum, you can see that most of sunlight is useless for plants, only a little fraction ( maybe 10 percent if any) is useful for photosynthesis.
If you look at ms 1300 sensitivity curve, you can see, that device is most sensitiv between 500-550 nm, sensitivity fall steeply in other wavelength.
Fluora tubes have three main emission spike, it takes cc. 75-80% of total emitted energy.One at 440 nm, one at 550 nm, one at 660 nm. So if you measure emitted energy of Fluora tubes with ms 1300, you mainly measure the energy of emitted 550 nm, because sensitivity of device at 440 and 660 nm is more less.
Light request of plants are "calibrated" to sunlight, so if you say, that XY plant needs eg.10000 lux, it means that XY plant needs about 1000 lux "useful" light energy.


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## Ray (Feb 26, 2013)

While it is primarily the red and blue wavelengths that are used in photosynthesis (more than 10% of the visible spectrum, by the way), plants actually absorb and use all wavelengths in that spectrum.

The old explanation that " plants look green because the plant doesn't use those wavelengths, so reflects them" is only partially true, at best. They do use green wavelengths, but the tissues actually reflect some percentage of all wavelengths, and the human eye is particularly sensitive to green, hence the appearance.


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## TyroneGenade (Feb 26, 2013)

Rick is correct. If you look at the data (shown below) you will see that plants really do use green and yellow light. In our experiments with aquarium plants we have found that the best tubes are those that offer the most balanced spectrum. 







In addition, lux is a really bad measure of useful light. Lux meters are skewed towards yellow:





Plants use mostly the red and blue together with the yellow/green spectrum. If you want to perform light experiments you need a PARmeter which can measure PPFD.


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## DavidCampen (Feb 26, 2013)

dodidoki said:


> These Fluora tubes have special spectral emission: there are two spikes at 440 nm and 660 nm. These two spikes are about 70% of total energy what these tubes produce.
> Sunlight has a continous spectral emission, there are no special spikes in its spectral distribution. Maximal absorbtion of chlorophylles drops very steep within +/-7-8 nm from 440 and 660 nm so useful range of sunlight is only about 2x15 nm. Total visible spectrum starts at 400 and ends at 700, so useful part of visible light is only about 10 %( of sunlight).
> 
> 10 % (sun) vs. 70% (Fluora)
> ...



Chlorophyll is only one of the plant pigments that absorb light for photosynthesis. With the additional pigments; photosynthetically useful light is absorbed over the entire range from 400 nm to 700 nm.


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## DavidCampen (Feb 26, 2013)

dodidoki said:


> Light meter sensitivity is calibrated for sunlight energy distribution.


Light meters are most often calibrated to match human visual sensitivity.


> As you look at sunlight spectrum, you can see that most of sunlight is useless for plants, only a little fraction ( maybe 10 percent if any) is useful for photosynthesis.


As several people have stated; this assertion is not correct.


> If you look at ms 1300 sensitivity curve, you can see, that device is most sensitiv between 500-550 nm, sensitivity fall steeply in other wavelength.


This means that that device is mostly useless for quantitative (or even relative) measurements of photosynthetically active radiation whether it be from the sun or a Flora fluorescent tube.

With the meter that I have; I removed the green filter that strongly biased the sensitivity to 550 nm. Now at least it gives decent relative measurements.


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## DavidCampen (Feb 26, 2013)

TyroneGenade said:


> There is a handy list of conversion factors at http://www.apogeeinstruments.co.uk/conversion-ppf-to-lux/


Their conversion chart may be OK but I have a problem with their PAR sensors - they put in a filter that stops any light with a wavelength greater than 650 nm! And they think that this is some sort of "innovation". I can't imaging what they are thinking. A filter would be fine but it shouldn't have a cutoff until 700 nm. It is too bad, I have been looking for a reasonably priced, calibrated PAR meter but Apogee has ruined theirs with this filter.

http://www.apogeeinstruments.com/content/Quantum-Sensors-LEDs-Downing-College-September-2012.pdf

Edit: Perhaps the 650 nm cutoff of the Apogee sensor is due to the sensitivity of the photodiode that they use versus the photocells that are used in other sensors.


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## DavidCampen (Feb 26, 2013)

Here is a useful PAR sensor, it is filtered to give a reasonably flat response between 400 nm - 700 nm and it does not cutoff until 700 nm.
http://satlantic.com/sites/default/files/documents/PAR-18May12.pdf


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## dodidoki (Feb 26, 2013)

I removed the green filter that strongly biased the sensitivity to 550 nm

Thanks, David! Very good idea!


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## DavidCampen (Feb 26, 2013)

I would like to calibrate my light meter now that I have removed the green filter. There is this website that gives information need to use the sun as a calibration source. 
http://clearskycalculator.com/quantumsensor.htm

The one problem is that now that the green filter has been removed the photocell (which I am assuming is silicon) will be sensitive to light with wavelengths as long as 1100 nm. This doesn't matter with fluorescent or LED lights since they are not emitting much above 700 nm but it will matter when trying to use sunlight as a calibration source. I need to find an inexpensive filter with a cutoff of 700 nm.

Edit:
Here is a filter that would work well - "750nm Dichroic Shortpass filter", but expensive at $85.
http://www.edmundoptics.com/optics/...hroic-shortpass-filters/3344?showall#products

Here are some more, less expensive filters.

These are very good and there is one for $33.50
http://www.edmundoptics.com/optics/optical-filters/shortpass-edge-filters/ir-cut-off-filters/1328

For these (KG-1) the passband is not quite as desirable but they are also less expensive - $17.50
http://www.edmundoptics.com/optics/...e-filters/schott-kg-heat-absorbing-glass/1934


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## Ray (Feb 27, 2013)

Any thoughts on these?

http://www.specmeters.com/lightmeters/


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## dodidoki (Feb 27, 2013)

Ray said:


> Any thoughts on these?
> 
> http://www.specmeters.com/lightmeters/



Very interesting, escepiaclly light meter FOR plants....I think ,maybe could be useful David's idea, using special filter ( green-lite filter).


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## DavidCampen (Feb 27, 2013)

Ray said:


> Any thoughts on these?
> 
> http://www.specmeters.com/lightmeters/



These have issues. The spectral response of their Quantum Light Meter is given at the bottom of page 3 here:
http://www.specmeters.com/assets/1/22/3415F.pdf
It shows that (assuming that they are using a silicon photocell) they have added a poorly chosen filter that absorbs in the blue around 400nm - 500nm and again in the red where there is a sharp cutoff around 630nm - 650nm. 

That their filter was poorly chosen is reinforced by their comments in the middle of page 3 about having to apply correction factors for different sources of light. This shouldn't be. A silicon photocell produces a signal that is proportional to the number of photons striking it and and a silicon photocell has a flat response between 400nm and 1100nm. When measuring quantum PAR, a photon (between 400nm and 700nm) is a photon; no correction for different light sources should be necessary.

For reference, here is the spectral response for a bare silicon photocell:
http://pvcdrom.pveducation.org/CELLOPER/spectral.htm
Red is the response of an ideal silicon photocell and blue is the response of a typical silicon photocell.
(actually it is not quite bare, the cutoff below 400 nm is due to a glass window on the cell). 
The graph is sloped because it is showing response versus wavelength as input power is held constant. At constant input power the flux of blue photons at 400 nm is 2/3 the flux of red photons at 600 nm. If the graph was plotted to show sensor response versus wavelength as photon flux was held constant then the graph would show a flat, horizontal line. A Quantum PAR meter should measure photon flux irrespective of wavelength.

The correct filter to use over a silicon photocell to give a Quantum PAR sensor is this:
http://www.edmundoptics.com/techsupport/resource_center/product_docs/curv_55234.pdf
or this:
http://www.edmundoptics.com/techsupport/resource_center/product_docs/curv_69183.pdf


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## DavidCampen (Feb 27, 2013)

Specmeters' Silicon Pyranometer is a bare silicon sensor:
http://www.specmeters.com/weather-monitoring/sensors-and-accessories/sensors/light-sensors/
The spectral response is given on page 2 here:
http://www.specmeters.com/assets/1/22/3670I_3670WS2_Pyrano_Sensor.pdf

If you added an IR cutoff filter to that sensor then you would have a good Quantum Par sensor.

Li-Cor knows how to make a proper Quantum PAR sensor, the spectral response for their Quantum PAR sensor is shown here:
http://www.licor.com/env/products/light/quantum_sensors/

I don't understand why these other companies can't make a correct Quantum PAR sensor.

This company also makes a bare silicon photocell pyranometer that just needs the addition of an IR cutoff filter to make a proper Quantum PAR sensor:
http://www.apogeeinstruments.com/pyranometer/
This company's Quantum Par sensors though have a sharp cutoff at 650 nm making them useless in my opinion. Instead of a silicon photocell in their Quantum PAR sensor they must be using an LED that emits at 650 nm as a photodiode.
Here is a comparison of the Apogee Quantum PAR sensor and Quantum PAR sensors from 3 other companies:
http://www.apogeeinstruments.com/content/Quantum-Sensors-LEDs-Downing-College-September-2012.pdf

Edit:
Another company that sells a bare silicon sensor. The physical form of this sensor might make it easier to place a filter of your choice over it.
http://www.solarlight.com/products/pma2140.html


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## likespaphs (Feb 27, 2013)

anyone know about the induction lights such as the ibeam from brotherhood products?
i'm leaning towards getting one of these

http://www.brotherhoodproducts.com/v2/products_detail_33.html


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## DavidCampen (Feb 27, 2013)

likespaphs said:


> anyone know about the induction lights such as the ibeam from brotherhood products?
> i'm leaning towards getting one of these
> 
> http://www.brotherhoodproducts.com/v2/products_detail_33.html



I have not heard of these. I just started reading at the website but already I see BS (or an inability to perform a simple arithmetical calculation):
_Lower wattage requirements for PAR usable light saves between 60-70% of the energy consumed by lamp technologies such as HID. _
That statement even contradicts a graphic on the same page that equates 600 watts of their lamp to 1000 watts of HPS or HID; that would be a 40% savings. Perhaps they just did the arithmetic incorrectly when they calculated the 60-70% savings.

Then when I go to the link they give for more information:
http://www.inda-gro.com/
I see that this is just a fluorescent lamp. *I see no reason to believe that these lamps would be more efficient than HID or HPS.*


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## DavidCampen (Feb 28, 2013)

Ray said:


> Any thoughts on these?
> 
> http://www.specmeters.com/lightmeters/



So, if you want to accurately measure Quantum PAR, the least expensive option that I have found is to buy an Apogee MP-200 Pyranometer with Handheld Meter for $410 and then add your own high quality IR cutoff filter (about $50). 
http://www.apogeeinstruments.com/pyranometer-separate-sensor-with-handheld-meter-mp-200/

A similar setup can be purchased from Spectrum for about $530 ($250 for the sensor, $280 for the meter) and again you need to add an IR cutoff filter.
http://www.specmeters.com/weather-monitoring/sensors-and-accessories/sensors/light-sensors/
http://www.specmeters.com/lightmeters/light-sensor-reader/

Or you can go to Li-Cor and for about $400 you can get a sensor that does not need an added IR cutoff filter. Then the Li-Cor meter is about another $700 for a total price of about $1100.
https://licor.secure.force.com/catalog/LI_ProductListMain?categoryID=a0d60000000T9PvAAK&store=env
https://licor.secure.force.com/cata...T9PuAAK&navigationStr=ListProduct&searchText=


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## keithrs (Feb 28, 2013)

DavidCampen said:


> *I see no reason to believe that these lamps would be more efficient than HID or HPS.*



What do you mean by efficient?

They are far more efficient the hid in energy use and bulb life.


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## Rick (Feb 28, 2013)

Generally light bulb efficiency is based on the amount of wattage that goes into producing light in non infra red (heat) frequencies versus heat production.

Unless you are buying a light bulb to generate heat in the first place.


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## DavidCampen (Feb 28, 2013)

keithrs said:


> What do you mean by efficient?
> 
> They are far more efficient the hid in energy use and bulb life.



I see no evidence and no reason to believe that these bulbs would be as efficient in producing light for photosynthesis as are MH or HPS bulbs. You will not save electricity by replacing T8 or T5 fluorescent or MH or HPS grow light sources with these other bulbs. Why do you believe otherwise?


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## keithrs (Feb 28, 2013)

DavidCampen said:


> I see no evidence and no reason to believe that these bulbs would be as efficient in producing light for photosynthesis as are MH or HPS bulbs. You will not save electricity by replacing T8 or T5 fluorescent or MH or HPS grow light sources with these other bulbs. Why do you believe otherwise?



They do not produce as much light as mh, lps, or hps as far a lumens. But you have to rise hid fixture about 18-24" above the plants so the light at the plants is equal to or less then an induction. You can place an induction light 6" above the plants. I have seen side by side comparison 1000 hps vs 400 induction and the growth was equal with slightly better flowering on pepper plants. To run hps you also need to run a fan over the fixture and possibly an a/c unit. Not to mention how much more light penetrates the canopy with induction because of how close you can run the fixtures to the plants.


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## DavidCampen (Mar 1, 2013)

keithrs said:


> They do not produce as much light as mh, lps, or hps as far a lumens.


That is what I am saying, I would expect that HPS lamps would be more efficient at converting electricity to useful light than these electrodeless fluorescent lamps. The electrodeless fluorescent lamps would have an efficiency about the same as standard T5 or T8 fluorescent lamps.



> But you have to rise hid fixture about 18-24" above the plants so the light at the plants is equal to or less then an induction. You can place an induction light 6" above the plants.


So an HID fixture of equal power would light a larger area? Then this would again confirm that these electrodeless fluorescent lamps are less efficient than HID lamps.


> I have seen side by side comparison 1000 hps vs 400 induction and the growth was equal with slightly better flowering on pepper plants.


Were both lamps were illuminating the same area (number of square feet) of plants?
Your other statements would indicate that this is not the case and again the electrodeless fluorescent lamps would not be as efficient as HPS. Where did you see this demonstration? More illuminating (a pun, but not intended) would be to use a Quantum PAR meter to measure PAR output from an electrodeless fluorescent lamp and calculate the value of micromoles of PAR per watt-second for these lamps. For comparison, using data from a Philips Horticultural Lighting datasheet, I got these values for the efficiency of their lamps; T8 fluorescent - 1.2 micromoles per watt-second, 660 nm (deep red) LED - 1.6 micromoles per watt-second and (600 plus watt lamp) HPS - 1.9 micromoles per watt-second. MH is slightly less efficient than HPS. I would expect electrodeless fluorescent lamps to be about as efficient as T8 fluorescent lamps and thus less efficient than deep red LED, MH or HPS. The efficiency values for MH and HPS lamps are for lamps of at least 600 watts; smaller lamps become much less efficient.

Here is a brochure from Osram about their Endura® line of electrodeless fluorescent lamps:
http://www.osram.com/media/resource/hires/333886/endura-quicktronic-system--qt-endura.pdf
On page 3 they state -*The luminous efficacy of the ENDURA® is comparable to that of fluorescent lamps.*


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## Ray (Mar 1, 2013)

DavidCampen said:


> For comparison, using data from a Philips Horticultural Lighting datasheet, I got these values for the efficiency of their lamps; T8 fluorescent - 1.2 micromoles per watt-second, 660 nm (deep red) LED - 1.6 micromoles per watt-second and (600 plus watt lamp) HPS - 1.9 micromoles per watt-second. MH is slightly less efficient than HPS. I would expect electrodeless fluorescent lamps to be about as efficient as T8 fluorescent lamps and thus less efficient than deep red LED, MH or HPS. The efficiency values for MH and HPS lamps are for lamps of at least 600 watts; smaller lamps become much less efficient.



If I am to follow your argument, David, the data says that the deep red LED is 33% more efficient than the T8. However, you will never be successful trying to grow a plant under a light source as narrow as 660nm.

There's electrical efficiency, and then there's _plant-growing efficiency_, as it relates the combination of power and wavelength.

It seems to me that while an HPS bulb puts out a great deal of light, a lot less of it is what the plants need, but that by compensating by increasing the power, the "mass" of light emitted in each wavelength is enhanced to the point of reaching minimum requirements.


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## DavidCampen (Mar 1, 2013)

Ray said:


> If I am to follow your argument, David, the data says that the deep red LED is 33% more efficient than the T8. However, you will never be successful trying to grow a plant under a light source as narrow as 660nm.
> 
> There's electrical efficiency, and then there's _plant-growing efficiency_, as it relates the combination of power and wavelength.
> 
> It seems to me that while an HPS bulb puts out a great deal of light, a lot less of it is what the plants need, but that by compensating by increasing the power, the "mass" of light emitted in each wavelength is enhanced to the point of reaching minimum requirements.



Yes, I should not have included any data for LED or HID. It is not necessary to my argument and is just distracting from the argument. Ignore anything I said here about LEDs and HID. Let us compare electrodeless flurorescent only against T8 fluorescent. The LED and HID information were just additional interesting datapoints that were not necessary; I really should know better than to include any information that is not absolutely necessary to support my thesis. Let me state this very simply so that, I hope, there will be no confusion:
*Electrodeless fluorescent bulbs produce light of the same quality as standard T8 fluorescent and are no more efficient at doing this than T8 fluorescent.*


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## keithrs (Mar 2, 2013)

DavidCampen said:


> That is what I am saying, I would expect that HPS lamps would be more efficient at converting electricity to useful light than these electrodeless fluorescent lamps. The electrodeless fluorescent lamps would have an efficiency about the same as standard T5 or T8 fluorescent lamps.
> 
> 
> So an HID fixture of equal power would light a larger area? Then this would again confirm that these electrodeless fluorescent lamps are less efficient than HID lamps.
> ...



The "test" was performed at my local hydro store. The system used was an aquaponics system with 4 fish tanks feeding both sites of test plants that where on floating rafts. The sq ft of plant was the same but I can't be certain that there where the same number. The lights where placed at the same height(18") and the fluoro seam to have a wider spread over the hps most likely do to the reflector used and was probably why hps only fell even. The test was performed for 8 weeks. 

There is a company making different spectrum bulbs for these fixtures. 

Think that even if hps is more efficient at converting light, I would still run fluoro. HPS just run way to hot for most grow spaces without running cooling of some sort. Plus if you some how get moisture on the bulbs, they can explode. But for the sake of just what's more efficient at converting electricity, then hps wins. But fails every other efficiency test in my book.


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## DavidCampen (Mar 2, 2013)

keithrs said:


> Think that even if hps is more efficient at converting light, I would still run fluoro. HPS just run way to hot for most grow spaces without running cooling of some sort. Plus if you some how get moisture on the bulbs, they can explode. But for the sake of just what's more efficient at converting electricity, then hps wins. But fails every other efficiency test in my book.


Yes, HID lamps have some operational difficiences, that is why I use T5 fluorescent lamps (and LED lamps of my own design) for supplemental light in my orchid room. 

I believe that you can solve the problem of HID bulbs exploding when they get water on them by using a fixture with a tempered glass window but they still tend to explode if you operate them for too many hours without replacement though this is mitigated if you use a fixture with the tempered glass or a Type O bulb that has an additional outer envelope that functions to contain the inner bulb if it explodes. Other difficiencies that I find more undesireable are the requirement to wait a quarter hour or so before restarting a lamp that has been shut off and the light source is too concentrated for my purposes. Also, to get the high efficiencies of HID lamps you need to use bulbs that are 600 watts or 1000 watts; lower wattage bulbs are much less efficient.

Looking at this chart on the Inda-GRO website:
http://www.inda-gro.com/gallery/album/9#5
I see that a difference they claim for their tri-phosphor bulb over standard fluorescent tri-phosphor bulbs is that the green emmision has been reduced in favor of enhanced blue and red. They say that this is an advantage because you don't stress the plants when you switch from MH lamps for growth to HPS lamps for flowering - you can use their lamps for both. 

They then imply that you can't get standard fluorescent lamps with this enhanced blue/red spectrum. I had actually started looking in to this some time ago, there are a lot of enhanced spectrum T5 and T8 fluorescent lamps on the market and I thought that I should be able to find some that reduced the green emission in favor of the blue/red. I stopped looking because I did not think paying $15 for an enhanced spectrum 54 watt T5 bulb versus a couple of dollars for a standard hardware store T5 was worth the extra cost, but if there is really some significant additional advantage to the enhanced spectra then it seems that paying extra for enhanced spectra T5 would be a lot less expensive than the Inda-GRO electrodeless fluorescent fixtures.


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## keithrs (Mar 2, 2013)

There is another company named I-Grow that has red and blue spectrum bulbs for these electrode less lamp put there like $250 last I checked. 

My seedlings do just fine under 6500 t8. But if I had the cash I would run one of these lamps.


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## DavidCampen (Mar 2, 2013)

You can get the same spectrum and efficiency for less money with T5 lamps. I would suggest a combination of the Aquatic Life Marine 460/620 lamp and the Aquatic Life Freshwater 650 nm lamp.
http://www.aquaticlife.com/sites/default/files/specsheets/410225.pdf
http://www.aquaticlife.com/sites/default/files/specsheets/410136_0.pdf


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## newbud (Mar 6, 2013)

I have about 40 plants in my basement under 4 HOt-5's w/one of Rays led's bringing up the end. 

Data: 1) Turn on lights at 6am.
2) Turn off lights at 10pm.
3) Plants are still nice and green and growing. 
4) They should make it until April when they go back outside.
End of Data.


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