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Possible LED layout

Im trying to figure out the layout for a LED grow light Im going to build for a 10 gallon terrarium; so far, Ive read quite a bit of conflicting opinions on the matter. I think Im set on including both colored and white LEDs; Ive drafted a possible layout, Im just not sure whether to include green or violet LEDs, or if this layout would even be satisfactory for growing carnivorous plants...
<a href="https://www.flickr.com/photos/pk93/14536922933" title="LED-layout by feverdreamt, on Flickr"><img src="https://farm3.staticflickr.com/2912/14536922933_a5ed57a62f_s.jpg" width="75" height="75" alt="LED-layout"></a>
Any advice would be greatly appreciated, thank you!
LED reply

Hello. I am seriously into LED lighting for reef aquariums and now CP's. I recommend the following "colors" if you get them from the right source. The source is RapidLED.com. First off... you're going the wrong way to look for "colors." The deal is wave length. Wave lengths for plants go from 400nm to 700nm... same wave length span for live coral reef aquaria. The wave lengths sold by RapidLED meeting these plant requirements are cool white; royal blue; ultra violet; red and green. One string of 14, 3 watt Cree LED's will work off one 15 dollar ballast. Each Cree LED costs 5 dollars. I have 60, 3 watt Cree's on one of my CP
terrariums... a 40 gallon open top standard issue fish tank and 27, 3 watt Cree LED's on a reptile tank I use solely for CP's. Everything is growing and flowering nicely and has been for a year now. Anyway, do include ultra violet and green in your layout. Look at the spec data on that site and look up what wave lengths plant need to floursh and you'll see what I'm saying. You should go for the 80 degree lenses or you'll
' spot light ' with anything smaller. This company is great on support... you can call them up and get top rated tech advice. The drawback is that LED technology is not cheap. The layout you show needs to be re-thought out. I see only 2 whites which is not enough... the blues and reds will dominate and it wont look like your plants are outside in the sun... your 10 gallon guy will look synthetic. Contact me if you need further help.
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At the upcoming ICPS conference in Cairns there will be an overview on growing CPs with LEDs. I've heard that a few commercial friends of mine are planning a major switch to them. I'll consider it, but until I *see* results, I'm not sold. I'm curious PK93: what made you decide to go with LEDs? And Mike66: do you have a picture of the layout? Plants? The switch to LEDs might be the next best thing since I made my T5 setup.
Thanks for the replies!
Mike66, I looked into the wavelengths of the LEDs and tried to choose LEDs that would match the wavelengths of light absorbed by plants most during photosynthesis and was considering green (I read it was beneficial somewhere on this forum I think, I just can't remember where) and violet, I listed the wavelengths for each LED in the picture I attached, however I don't think I attached the picture correctly because it is displayed rather small and a portion of it was cropped off, my apologies. Thanks for the source too, they carry some LEDs that the other sources I was looking at didn't have, I'll definitely consider them!
Apollonian, I like the option of customization (the heat sink Im going to use will allow me to edit the layout of the LEDs or add/subtract LEDS if I need to), being able to control which LEDs I want to include (and in turn which wavelengths of light), and that they should be much more efficient than other available light sources (other than the sun, that is :p)
.. I actually drafted another possible layout today, I think this one might be better..

Woohoo, I attached the picture correctly this time!!
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This is *fascinating*! So you can control wavelength output of a layout by opting certain bulbs, and these bulbs are apparently easy to secure on the market... I am definitely looking forward to hearing the talk in Oz about all this.
I could ask which bulbs seem to be most beneficial to which plants, but observing that you've got a lot of different colored/wavelength bulbs per layout, then I'd say it requires several bulbs to satisfy a plant, which would make sense, assuming that plants need multiple wavelengths to survive. Am I on the right track? Are you using reflectors?
*Edit* Just went through those links. I'm really impressed! My cephalotus could really use the help. It looks like a new experiment is in order...
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Apollonian, I think so too! Yes, since different types of LEDs produce light of different wavelengths, you can choose which wavelengths of light to include on your fixture (white light includes many wavelengths along the spectrum of visible light). Do you know if the talk is going to be filmed/streamed onto the internet? I wish I knew which lights are best for which plants, it would really help; Im not sure if there is even any research on the subject that has been made public :(.
RSS, sorry for not responding to your reply, I somehow failed to see it :(. I've read some of those posts before and they have certainly helped, thank you! Your plants look like they are really doing well under the LEDs too. I think Im going to have to figure out how to raise my fixture once I build it (as opposed to just having it sit on the lid of the terrarium), seeing as some of the plants Im going to set on a false bottom I have built won't be more than 3 inches away from the lid (I suppose I could shorten the false bottom); a picture of the false bottom in the terrarium can be found here
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Why are you using purple, turqoise and green? As most plant lights use deep red and royal blue. Haven't heard that plants benefit from those extra wavelengths. I myself have built led lights, with only 660 nm red, 452 nm vlue and cool white 6500 K for visual reasons. The results are very good.
  • #10
Thanks for the replies!
Sorry for the late response, I included the violet LEDs to try and provide more wavelengths of light that plants absorb during photosynthesis, the light given off by the violet LEDs may not be utilized as much as blue or red light, but I think it might be beneficial to cover more of the spectrum; I have included the turquoise (just realized the typo in the attached picture.. I also forgot to include the wavelength for the royal blue LEDs :blush:) and green LEDs in the picture mostly for display/aesthetic purposes (I want the plants to still look somewhat green while the lamp is on), however, I read here that green light is important for canopy penetration..
I have yet to order anything since Im still trying to figure out how many of each LED to include and how I want to organize them on the heat sink.
  • #11
After some further reading, I think I need to reduce the amount of LEDs I have planned for the lamp if I am going to set the fixture on the top of my terrarium like I had planned; the plants will probably be 4-8 inches beneath the LEDs..
I could probably use the same amount of LEDs but run them at a lower current, but Im not sure if that would make much sense..
  • #12
Are you using reflectors?
I found this little thing at a tropical fish store near me: https://www.flickr.com/photos/124993450@N07/14406311468/
It's a strip of LED lights to be plugged into a fixture. Gives red spectrum light. I'm guessing I could combine strips of different colors to match the requirements of my Drosera.
I confess that I find it very difficult to follow units of light measurement.
Apparently there has been some success growing Dionaea with LEDs on this thread from 2009: http://icps.proboards.com/thread/2932?page=1
  • #13
LED's are getting quite common. If you have a local hydroponics/grow room store, you'll find tons of them there. I know the local one carries them, but they sell these whopping huge fixtures that are ridiculously expensive! Not to say I haven't considered them, just that I am waiting for prices to come down.

Many hardware stores now also sell LED's in many formats - cables that are fairly weatherproof for indoor/outdoor use, available in different colors for the sake of being 'festive'. I don't know how well those might work in combination with other lights, but they are really affordable, and I do use them to illuminate one of my nicer snake cages.

That said, I have done some reading about the value of different wavelengths of light (which translates into different colors - only some of which are visible to the human eye.)
  • #14
I believe China sells knockoff varieties for cheap. ...not that I endorse Chinese knockoffs.
I have a good command of the color spectrum measurement units (kelvin and amplitude per color, what these mean to plants) and I feel that anything that gives good blue and red-yellow light should be great for sundews, but this conclusion is arrived at solely on account of hearsay and I have nothing scientific to say about exactly why.
I've noted that many LED fixtures available for fish tanks are composed of about 10% useless display lighting.
While we're at it, ultraviolet wavelengths may be valuable for plants coming from higher altitudes where ultraviolet light hasn't yet dissipated. Google reveals that ultraviolet LEDs exist.
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  • #15
Apollonian, since I plan on having my lights pretty close to my plants, I don't think I will be using lenses/reflectors as they might inhibit the the light from blending. Those LED strips might work, but you would need to find out the wavelengths of light they give off; if they are made for planted tanks they might work, but if they are made for rearing coral, they probably wouldn't be very efficient for growing plants. I don't know anything about the Chinese LED "knockoffs" but I assume you get what you pay for (not always true of course). I think you would want to include deep red LEDs (660nm), royal blue LEDs (450nm), then other other LEDs to cover more of the light spectrum (even green for canopy penetration).

Dragoness, I really need to make it down to a hydroponics store one day, I wonder if some sell individual LEDs (mounted).. Im not sure if the LEDs at most hardware stores would be fit to grow plants (especially plants that require high amounts of light)
  • #16
I'm no LED expert but I'm still very confused when I read over this thread, what LED types are you planning on using? The local pet store LED pre-made strips/bars are no where near the intensity of the CREE XP-G, Phillips rebel, ect. I've never seen a positive response to there strips/bars use besides adding some reds/blues to existing T5/T8/CFL setups. I can tell you from experience that I can stare into one of those 100 bulb LED fixtures and its annoying, if I stared into 4 of the CREE XP-Gs I'm using I would be seeing "sun spots" for a while. They are not in the same class of lighting.

Not all LEDs are created equal, you have to do your reading.

With such a small area a blend of the white LEDs would be better imo.
  • #17
They do make LED's in different wavelengths of UV. Including UVC, which is primarily used to sanitize anything from aquarium water to toilet seats, as that wavelength is germicidal.

There are also limitations to how far it is projected from it's source (the bulb). Many LED's with UV can only project the UV about a foot. I believe a spectrometer would help establish how useful that would be in a terrarium.
  • #18
you also must consider cooling,

High power LED's require cooling or they begin to lose efficiency (and color shift in the case of white LED's) from the moment they first get hot.... and they do get very hot if you let them.
Passive or active cooling mitigation is required for long life... each time they get hot, they suffer some permanent damage


you will also need some good thermal epoxy if you're going to mount them to the heatsink yourself, etc etc etc.....
as RSS recommends, be sure you do your homework before you start ordering anything.

Constant current driver, variable output is nice
(you will need a VOMa meter to set the output if you don't have one, typically you cant push the far reds as hard as some of the other colors, so they will be the limiting factor current wise)
proper heatsink (large if passively cooled, plus fan if actively cooled)
Thermal epoxy
Aux optics if you choose to use them
filter capacitor, 2200uf @35vdc is fine (you may or may not use this depending on your power supply)

Hard part about LED's is keeping them in good shape over the long haul.... .
You gotta keep em cool
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  • #19
Oops, somehow I forgot to mention what type of LEDs Im going to use..
RSS, I plan on using high powered LEDs (probably Luxeon Rebels or Crees) and mounting them onto the 18" version of this heat sink since it should be reusable if I decide to change the layout of the LEDs, add more, or update the LEDs if/when the need arises.. this heat sink is designed to have the LEDs mounted with screws and thermal grease rather than thermal epoxy.

Av8tor1, thanks so much for that link, I was wondering how to figure out whether the heat sink I want to use would work effectively.
I was planning on using this driver since it is made to mount on the heat sink I was also considering; It has two Meanwell LDD series drivers in it, so I will be able to run two different strength currents; the fact that it is dimmable may come in hand if I need to emulate sunrise/sunset down the line.
I probably won't use optics because they might focus the light too much at the hight I will have my fixture (4-8 inches above the top of my plants).. I would like to have my fixture further away from the top of my plants but Im not sure how to achieve that without hanging the fixture from the ceiling, which wouldn't be ideal for my space..
I read this thread and am now looking into the custom Luxeon tristars; I think being able to have different LEDs mounted on one star would allow me to include different wavelengths of light and still allow them to blend at the hight I plan on setting my fixture. Are you still using the tristar you ordered? If so, how has it worked so far?
  • #20
I think you will find 4-8" of height with high power LED's being driven at max is way more than you might expect, even without accessory optics..
This is where they variable current driver will be of benefit more than emulating a sunrise/sunset effect.

Looking directly at my tristar for just a few seconds at full power would result in seeing spots and a rather nasty headache. These aren't your run of the mill, ebay/hydro shop/ flying saucer LED's.

The ones I used are obsolete now I think, HP LED's technology is where computer microprocessor technology was 15-20 yrs ago. What you buy today is obsolete in six months. The ones that replaced mine have a lower junction temperature I think.

They worked great for low canopy plants, such as sundews, cephs etc.... but more would be needed for heliamphora or nepenthes. Using the close plant to light distance with higher canopy plants resulted in a lot of shading and diffraction. IMHO, you want more distance (tristar to plant and tristar to tristar), and more light sources to prevent these issues.

Speaking purely for myself, I'm going to wait for the technology to mature a bit more before I spend any serious coin on an LED system. Currently, T5's just work too well in my application.

They are cool to play with and one day will be the light of choice for me as well
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