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manders

LED experiment.

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I have a fish tank terrarium with 200w Envirolite and 50W 4 band LED at either end. Unfortunately different plants scattered around the fish tank but maybe it will show how well the LED's are performing in a few months.

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Edited by manders

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I have a fish tank terrarium with 200w Envirolite and 50W 4 band LED at either end. Unfortunately different plants scattered around the fish tank but maybe it will show how well the LED's are performing in a few months.

4202464101_7797fef2a6_b.jpg

Will be an interesting experiment. Can I suggest to make this more fair you put plants that are the same type (if possible preferably cuttings from the same plant ie geneticlly identical) and of the same size and put them in the two different test conditions. This will make any results more valid.

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Will be an interesting experiment. Can I suggest to make this more fair you put plants that are the same type (if possible preferably cuttings from the same plant ie geneticlly identical) and of the same size and put them in the two different test conditions. This will make any results more valid.

The best i can do is spread the kuchingensis*Viking plants around the terrarium, they are seed grown rather than identical but there is several of them.

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I will be keeping an eye on this experiment as so far I have been quite unimpressed with LED growlights. I've never been sure if it was due to lack of power or spectral spread. 50W is substantially more power than I have tried and 4 bands is double the number of wavelengths that I've tried.

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I have a fish tank terrarium with 200w Envirolite and 50W 4 band LED at either end.

So you like to compare 200 watt of lighting power against 50 watt?

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So you like to compare 200 watt of lighting power against 50 watt?

I'm interested to see what the growth under 50W LED lights is like because so far I have been unimpressed with the lower power ones that I have tried. I believe this may be partially due to too little power and the LEDs I've been using only outputting two spectrums, of which the red was 635nm, which is not in the peak absorption band. I think that LEDs can be useful for plant growth, NASA have proved this, but I also believe that their setup was far more sophisticated than a bunch of common 5mm LEDs. I can't help but think that sulphur plasma lamps might surpass them unless the price for more powerful and better spectral output LED growlamps comes down.

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So you like to compare 200 watt of lighting power against 50 watt?

Thats exactly what it isn't...

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Wattage is simple the amount of electricity used. It says nothing about the light output of the bulbs. Consider the difference in a CFL using 13watts to put out the same lumens as a 60watt incandescent. LED are even more efficient than that. Estimates for 50w of LED would be equivalent to 200-250w metal halide HID in PAR value.

My concern with the LED is the cost to set them up and the peak wavelengths while close to chlorophyll A are not right on... As well they still need to be fairly close to the plants and hence would not be very suitable for what I would want them for.

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My concern with the LED is the cost to set them up and the peak wavelengths while close to chlorophyll A are not right on... As well they still need to be fairly close to the plants and hence would not be very suitable for what I would want them for.

Tony, the set up cost seems to be dropping rapidly, this 50W unit cost was similar to the 200W envirolite with the bonus that i shouldn't have to change the (expensive) bulb every year. Personally i'm less concerned about wavelengths being 'spot on', in addition to Chlorophyll A, there is Chlorophyll B, carotenes and xanthophyll's all absorbing at different wavelengths. As long as you are not producing substantial amounts of light between 490 and 570nm or thereabouts, it should be more efficient than white light.

It way to early to tell what the results will be, but at the moment the plants are definitely growing under the LED, have to see what happens long term.

I don't see why the lights need to be closer than any other artificial light?

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No they don't need to be mounted closer than other artificial light. The new more powerful bulbs can probably even be further away than standard fluorescent tubes. Savings in electricity and bulb costs are certainly a big factor and deffinately worthwhile consideration. The cost has been coming down alot with simultaneous improvements in the light output. I am not convinced they are there yet because yes the plant has other molecules to absorb solar radiation, chlorophyll A is still the primary one. I look forward to seeing how the plants develop. Photos I have seen of veggies grown under LED have all looked a little.. hmm odd to me.

I think they will be a viable lighting source for many indoor and hobby growers but as a supplimental greenhouse light to enhance the dull dreary days or to extend daylength during the Winter months they are currently impractical for my purposes. Which is why I say they need to be fairly close to the plants and hence would not be suitable for me at this point. A single 1000w halide can be mounted high overhead and cover many many square feet and still provide the light intensity required at the leaf surface. I just cant afford to run them!

Edited by Tony

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My main interest in using them would be as a supplemental lighting in winter (sometimes up here it feels like we are living at the northpole in winter with regard to light, with at least 4 months of inadequate light for the plants), although i do also have few terrariums that only get artificial light.

Most plant have chlorophyll A&B and that effectively spreads the absorption over a wider area. In addition the solvents used to extract the chlorophyll for the absorption experiments affects the results. Also in addition, there are synergistic effects of different wavelengths that simply aren't taken into account in those simple absorption experiments. (the absorption spectra don't follow photosynthetic efficacy precisely) The only way to know is to try, hence my (cheap) experiment.

Thy hype says that a 1000W MH could be replaced with a 250W LED, IF that is true it starts to look interesting for lighting for example my small greenhouse in winter. Those numbers seem to be based on red/blue light and using the previously mentioned absorption spectra as a theoretical basis. The newer lamps tend to be Quad or higher bands with he aim of getting better looking growth, therefore the efficiency will drop. Maybe the MH light can only be replaced with a 500 or 750W LED.

I think with the 50W LED i have got growth is already better than with 50W of fluorescent lighting and the light is covering a wider area. Whether it can match a 200W fluorescent remains to be seen. :biggrin:

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Had this going for about a month now, too early for real results but...

My small clipeatas love this, the humidity in the tank is very high, which may be part of the reason, but both my Wistuba Clone U and BE Clipeata are doing better than ever before. (unfortunately I lost a couple of others this summer in the conservatory so i'm down to only two). The pitchers are growing on every leaf and coloring up nicely. Same thing on a small ventricosa (which has allays been terrarium grown under 40-60W of fluorescent and struggled to pitcher) and also on a small Sanguinea which is also coloring up nicely.

The Viking * kuchingensis are growing slowly (these are essentially lowlanders and the tank is more intermediate) but too early to do a direct comparison between fluorescents and LED.

On the basis of what i'm seeing for the sanguinea, ventricosa, and especially the clipeatas i'm pretty pleased with the result so far. If the LED's were a bit cheaper i'd buy a few more...

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I have recently held a brief conversation with a genetics professor with a specific interest in mosses who has used LED illumination consisting of specialized Red, Blue and White ones. He told me that the wavelength of the light was critical. I am interested in LEDs for VFT seedlings. You can find single colour 50 watt and 100 watt LEDs on Ebay complete with the driver, fan cooled heatsink and lens to focus the light. I think it would be a reasonable experiment to grow some cress using them and the results would be quickly obtained with a fast growing plant like cress. The use of a lens would really zap a small area with a lot of light and would allow the LED to be further away to avoid any over heating problems.

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I have recently held a brief conversation with a genetics professor with a specific interest in mosses who has used LED illumination consisting of specialized Red, Blue and White ones. He told me that the wavelength of the light was critical. I am interested in LEDs for VFT seedlings. You can find single colour 50 watt and 100 watt LEDs on Ebay complete with the driver, fan cooled heatsink and lens to focus the light. I think it would be a reasonable experiment to grow some cress using them and the results would be quickly obtained with a fast growing plant like cress. The use of a lens would really zap a small area with a lot of light and would allow the LED to be further away to avoid any over heating problems.

Good idea, let us know how you get on. The LED's usually have lenses built in and typically cover something like 120-180 DEG. The 50W UFO i'm using at first was positioned too close to the plants and caused cell damage on the leaves, particularly on the Giant Tigers and Viking*Kuchingensis plants, so I would think twice before you are thinking of concentrating the light down from a 100W array into a small space.

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The dodgy HK build quality is starting to show, got home yesterday and half the LED's weren't lit up. Had to get the soldering iron out and do a quick by-pass operation to get it working. Luckily the same dirt cheap replacement LED's are available on Ebay!!

Still happy with the growth rate of the plants anyhow.

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Very interesting. I would be interested in a comparison with flourescent to give a watt/growth comparison. In theory the LEDs should be better as they target the "correct" spectrums. Now how do I justify buying one of these to the missus.... Any chance of an update photo?

Cheers

George

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The dodgy HK build quality is starting to show, got home yesterday and half the LED's weren't lit up. Had to get the soldering iron out and do a quick by-pass operation to get it working. Luckily the same dirt cheap replacement LED's are available on Ebay!!

Are the LEDs in series then? If so, wouldn't bypassing the failed one/s cause the existing ones in the chain to fail?

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Are the LEDs in series then? If so, wouldn't bypassing the failed one/s cause the existing ones in the chain to fail?

The LED's are in two series of 45 each. So supply voltage out of the driver should be ~110V, i need to get a meter to check. Removing 1 out of 45 LED's should have very little effect, the constant current drivers seem to work within a certain number of LED's e.g. 30-50 etc in series. I hope to replace the dud one soon.

Parallel LED's would give a great degree of reliability!

If the plant growth remains strong and I can figure out a good way of doing it, i might be tempted to build a DIY one. The electric part is easy just need to figure out a good way of heat sinking them.

George,

It's too early for a direct comparison, my gut feeling is though that i'm not seeing much difference between 50W of LED and 200W of fluorescent. There is some difference on the way plants color up, especially when too close to the lights, ill try get some preliminary photos tomorrow in the daylight.

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LED are even more efficient than that. Estimates for 50w of LED would be equivalent to 200-250w metal halide HID in PAR value.

Tony, this is not true (yet). There is a very good page in German language comparing different lights. The summarizing table at the end should be readable without german language skills:

http://www.hereinspaziert.de/Sehlicht_2009/Ergebnisse.htm

Compared to a good 70 W metal halide lamp, which are used quite often over here for plants, there is no significant difference in efficiency compare to good commercial available LEDs. Recent scientific results show LEDs being more efficient than commercial available Metal Halide lamps - but this efficiency won't be available for grow lights for some time I would expect.

The sellers of LED lights are all over exaggerating - and I have no idea why they do this... ;-)

Connecting LEDs in series is in general a good idea: The current flowing through all LEDs is the same and so the radiated power of all these LED is nearly the same. In parallel setup one would easily spot fabrication variations between the LEDs due to the differences in radiated amount of light.

In theory LEDs should last a very long time (depending on current running through them) - sadly this is not true for low quality LEDs used in cheap lamps. And those cheap LEDs also won't show good efficiency as well...

Joachim

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Tony, this is not true (yet). There is a very good page in German language comparing different lights. The summarizing table at the end should be readable without german language skills:

http://www.hereinspaziert.de/Sehlicht_2009/Ergebnisse.htm

My German is not good but it looks like the article says it takes 30 Cree XR-E Cool White LEDs to equal the output of a 36W daylight fluorescent. Have I read that right?

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Tony, this is not true (yet). There is a very good page in German language comparing different lights. The summarizing table at the end should be readable without german language skills:

http://www.hereinspaziert.de/Sehlicht_2009/Ergebnisse.htm

Compared to a good 70 W metal halide lamp, which are used quite often over here for plants, there is no significant difference in efficiency compare to good commercial available LEDs. Recent scientific results show LEDs being more efficient than commercial available Metal Halide lamps - but this efficiency won't be available for grow lights for some time I would expect.

The sellers of LED lights are all over exaggerating - and I have no idea why they do this... ;-)

Connecting LEDs in series is in general a good idea: The current flowing through all LEDs is the same and so the radiated power of all these LED is nearly the same. In parallel setup one would easily spot fabrication variations between the LEDs due to the differences in radiated amount of light.

In theory LEDs should last a very long time (depending on current running through them) - sadly this is not true for low quality LEDs used in cheap lamps. And those cheap LEDs also won't show good efficiency as well...

Joachim

My German isn't great either but the comparison seams to be various types of White light. The whole point of LED grow lamps is that they are essentially using blue and red light only and are therefore more efficient.

The manufacturers claims on a theoretical basis are perfectly valid.

40 Lumens of red/blue light is more radiant energy than 120 Lumens of white light, a large part of the white light cannot be used by the plants and plants only care about radiant energy, not lumens in any case. Or put another way, if you want a lot of lumens make the light green as that is what the human eye sees best, but it is zero useful radiant energy to a plant. Lumens is only a measure of how sensitive the human eye is to various colors of light.

The way i see it, there is not likely to be much difference between white LED's and any other form of white light, but thats entirely missing the point.

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First of all, this experiment has only been going for a month so any interpretation of the results is more gut feel than anything at this stage, well need at least several more months to really know. Anyway here are some observations i've noticed so far:

Firstly the tank conditions are around 18C +-3C, so basically intermediate. This is a problem for my main test plants (kuchingensis * Viking) which are really lowlanders. The test plants are form the same batch of seeds and are about a year old.

The light is positioned 20 inches above the floor of the tank. I would consider this normally to be too high for 40-50w of fluorescent light and the tank on the right in the photo which is lower, has 40w fluorescent on it and I use it for plants that don't tolerate a lot of light (Northiana and so on).

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So how are the plants doing with the LED?

Well Firstly a clipeata 'hybrid'. These are actually plants i've had real problems with, my greenhouse wasn't ready until early summer and these guys hate my conservatory (can only assume the light level isn't high enough).

So heres what happened after 4 weeks under the LED...

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A true clipeata, notice the new leaf is much greener than the previous photo, so its not the LED causing an odd colour, but something else. Also both leaves are showing signs of coloring red under the light.

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Small sanguinea, new pitchers are coloring up ok

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Small red tc'd ventricosa, this guy failed to pitcher at all in the 40W fluorescent tank.

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Two pitchers showing good potential coloration

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Now some odd effects of growing under LED!!

This is what happens if you place the LED's too close - you destroy the chloroplasts and the cells...

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Same plant placed further away and with new leaves

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So what does all that mean? Well, the 50W LED is clearly a lot stronger than 40W of fluorescent, as its placed much further away and the plants are doing much better under the LED, indeed when the LED was too close it damaged the plant and too close in this case was about the same distance as the fluorescents in the other tank. At the moment theres really no obvious difference between those under the 50W LED and those under the 200W Envirolite, so i haven't bothered with any photos. This should get clearer as the spring arrives, the temp warms up a little and the lowlanders, which are the main test subjects really get going.

This unit is using the 'wrong' wavelengths (630nm) so cant wait to get hold of one using 660 and see what that does...

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Some interesting pictures and is good to see someone giving LED's a real go.

At the moment theres really no obvious difference between those under the 50W LED and those under the 200W Envirolite

I bet there is to the cost of running them though ! How long will it take to break even with the savings from the LED's ?

If you go down the diy route, would you make the light more friendly to human eyes ? Keep the same number of blues & reds but maybe add a few whiter LED's ?

Cant help but think the plants under the white light "look" healthier to the human eye and possibly easier to see any possible health problems ?

Keep up the good work,

Joel

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Some interesting pictures and is good to see someone giving LED's a real go.

I bet there is to the cost of running them though ! How long will it take to break even with the savings from the LED's ?

If you go down the diy route, would you make the light more friendly to human eyes ? Keep the same number of blues & reds but maybe add a few whiter LED's ?

Cant help but think the plants under the white light "look" healthier to the human eye and possibly easier to see any possible health problems ?

Keep up the good work,

Joel

Hi Joel, a 90W LED replacing a 250W envirolite, assuming that is possible, would pay for itself in around a year. You would save 160W for 12-14 hrs a day, 365 days which is around an £85/yr of reduction on your leccy bill. In addition you wouldn't have to buy the large Envirolite bulbs every two years, which are expensive in their own right. No I wouldn't add whiter LED's as it would lower the efficiency, you could always rig up a separate white fluorescent light for just those times when you want to look at the plants.

Actually i should say this LED has 60 red, 10 Blue, 10 White and 10 Orange LED's.

Edited by manders

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The tank has been running for over six months now so should be good time to see the difference. The plants below were all about the same size when added to the tank and six months later theres not much difference between them in size. Those above were under the 50W LED and those below under the 200W Envirolite. As noted before, if too close to the LED it seemed to cause cell damage on the plants, which didn't happen with the Envirolite. ON the other hand the areas I could have lit with the LED could have been at least twice as much as I did. Take a look at the pic and Judge for yourselves I guess.

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