# [Wet Thumb Forum]-LED lighting



## AndyL (Jun 5, 2004)

Hey folks,

Lets discuss shall we, the use of LED lighting in planted aquaria. Gomer and I were discussing this tonight, and I think its time to go a step beyond discussion, and my 2g Hex would make a great test-bed.

http://www.theledlight.com/led-specs.html#Full_Spectrum_LEDs

This is my intended source for the LEDs, help me out - a lot of this stuff is greek to me







what the heck are the mcd they speak of in luminous intensity? I was thinking of just going ahead and getting the 2nd down - LED 20deg WH ; but is that the best choice?

Alternatively - tho it costs more http://www.theledlight.com/versalux.html looks like a pre-built module, just hook up a 12vdc power source and go... But it doesn't make any reference to temperature; which is somewhat bothersome.

What do you guys think/know on this topic?

Andy

Andy L

Man created Planted Fish tanks, God created algae.


----------



## AndyL (Jun 5, 2004)

Hey folks,

Lets discuss shall we, the use of LED lighting in planted aquaria. Gomer and I were discussing this tonight, and I think its time to go a step beyond discussion, and my 2g Hex would make a great test-bed.

http://www.theledlight.com/led-specs.html#Full_Spectrum_LEDs

This is my intended source for the LEDs, help me out - a lot of this stuff is greek to me







what the heck are the mcd they speak of in luminous intensity? I was thinking of just going ahead and getting the 2nd down - LED 20deg WH ; but is that the best choice?

Alternatively - tho it costs more http://www.theledlight.com/versalux.html looks like a pre-built module, just hook up a 12vdc power source and go... But it doesn't make any reference to temperature; which is somewhat bothersome.

What do you guys think/know on this topic?

Andy

Andy L

Man created Planted Fish tanks, God created algae.


----------



## Synapse (Mar 9, 2004)

Hey there, 

Happy to see someone had this idea too. Been looking into LED lighting quite some time ago, after reading a NASA study, they successfully grown plants in space using LEDs. 

mcd = mili candella 1000th of a candella... not much. That would mean you would need a bunch of them. 
If you want to use 12v supply( 3.6V * 30mA = 1.08W...) you would have to hook them in groups if 3 parallel led with a 1 ohm limiting resistors. 

Heat would not be a concern mainly because LEDs are verry efficient (up to 90% - 90% light 10% heat).

Also, leds have verry narrow bandwidth, so I would encourage you to choose two of more different led color to benefit plant growth. Something around 6000K and 8000K for exemple.

I couldn't tell you the exact number of leds needed but I do encourage you to try it and share your results.


----------



## AndyL (Jun 5, 2004)

Still researching trying to figure out how many LEDs and of what spectrum I'm looking for - figured I'd share some interesting findings...

First off - hydroponics guys are using LEDs now
http://www.ledgrowlights.com/index.htm

Then I found this from NASA - I know this has the info I need - but my brain can't comprehend the technobable... I need a cup of coffee then I'll start trying to read it again. http://www.dsls.usra.edu/meetings/bio2001/pdf/043.pdf

Now *IF* I understand right, the current research on growth has been done under red (660-690nm) LEDs, and blue (430-470nm) LEDs. Obviously this would look pretty sad in an aquarium (and may be stressful to the fish), but maybe with a mix of full spectrum white - a reasonable mix of growth and viewable/photographable light can be found...

Andy

Andy L

Man created Planted Fish tanks, God created algae.


----------



## deltalight (Dec 28, 2003)

Hi Wet Thumb Group!

Andy L suggested I jump on board for discussions on using LEDs for horticulture and aquaculture.

I was the first company to introduce LED illuminators to the public as general purpose lighting starting in 1993 with feature articles in Home Power magazine. The rest is history.

Andy, it's really a sad state of affairs when we pay NASA $$millions for their space program and they can't provide us with more information then they do. I've tried to get them to give me technical data from technical articles they've placed in NASA Tech Briefs. They are truly a farce. In any event, necessity is the mother of invention -- right? SO of we go and bypass NASA and their astroculture program. Their probably too spaced out due to growing the wrong kind of mushrooms they've made soup from --eh?

In any event, LEDs are expensive when put into arays sutable for plant growth. Recently, I've looked into mfg. LED lights for the salt water fish folks. I can desgn lights to be completely submersible if necessary.

Bill


----------



## SoCalSar (Feb 4, 2003)

Very interesting idea. I've done some research on LEDs also, but for different application than aquaria. LEDs are certainly well suited for certain applications, specifically where a highly efficient point source of light is needed to be viewed, but not necessarily illuminate something else. And they last forever. They make great car brake/tail lights, they're used on traffic lights now, perfect for keychain lights, ect. 

Their downfall is that they do not project. You'll never see an LED in an application where it's used to illuminate something else over any kind of meaningful distance. Their technology (currently) doesn't offer that capability. Unfortunately the ability to project, or penetrate, is exactly one of the traits we need in an aquarium. What we use is more similiar to the brightness of sunlight. LEDs are more like moonlight. 

Nevertheless, it's an interesting experiment. Maybe the small size of the tank will help the situation? Don't think I'd even try with a tank more than 12" deep. I do know that you'll need a large array (at least 50) to get the kind of light you would from one dinky halogen. Sounds like you would need to build or have built a custom array with white, blue, and red LEDs. The raw parts are actually not expensive but the custom work might cost you. I think I saw kits you can order online so that might be another option; you'd certainly save by building a kit yourself. Some soldering skill is about all that's required. 

I hope you go ahead and give it a try. If no one tries, then no one succeeds. Good luck.


----------



## AndyL (Jun 5, 2004)

> quote:
> 
> Their downfall is that they do not project. You'll never see an LED in an application where it's used to illuminate something else over any kind of meaningful distance. Their technology (currently) doesn't offer that capability. Unfortunately the ability to project, or penetrate, is exactly one of the traits we need in an aquarium. What we use is more similiar to the brightness of sunlight. LEDs are more like moonlight.


Um, are you thinking of the new LEDs or the old style ones that were used in your alarm clock? I've got a intrisically safe LED flashlight that outdoes my 5D maglight and another really expensive HID flashlight. They're now making street lights to light the highways out of LED arrays...

As a side note, I pulled out a 6 LED array (Luxeon stars, 470nm) that I bought for a Nano-reef that I've never gotten around to putting together. Even in that funky blue color - it lit up the 2g better than the 2 13w PC's do. I don't think penetration is an issue. I put it on my 55g, and the light was just as strong but not dispersed enough.

Bill: Thanks for stopping by, out of curiosity - what are you making for saltwater?

I've found some full spectrum 'ultra bright white' LEDs - I'll be buying a few, PDQ then its just prototyping the array and making it safe to use above the aquarium. I was just planning to use a good old radio shack prototyping board and once everythings installed - giving it a epoxy encasing to keep the water off the board. Just trying to decide whether I want some red/blues in with the full spectrum white.

Andy

Andy L

Man created Planted Fish tanks, God created algae.


----------



## AndyL (Jun 5, 2004)

Hmmm I think I'll post some links, to give some idea of how powerful these little things can be.

This is a 4 470nm 30degree 5w LED setup - used on a 4' 90G reef as a moonlight:









This is 2 470nm LEDs on a 10g reef, again moonlight. No specs other than 470nm...









12 470 Luxeons on a 28g bowfront as moonlight... These are the same LEDs I tested my theory on - on the 2g, except I only had 6.









Any questions on penetration now?









Andy L

Man created Planted Fish tanks, God created algae.


----------



## EDGE (Feb 28, 2004)

Here is an older post on DIY LED lighting by gsmollion

DIY LED lighting

72 Gal, 3 WPG PC 12 hour, pressurize co2 /w controller 3 bps, Fluval 404, ph 6.75
A Canadian's Plant Traders website


----------



## SoCalSar (Feb 4, 2003)

I stand corrected, sir. Are those setups using the bare LEDs on a circuit board or using some type of reflector?


----------



## AndyL (Jun 5, 2004)

Some of both, a couple they've just drilled a hole in the reflector - and stuck the bare LED through. Most of the others are simply the bare LEDs mounted one way or another.

As my LED project stands right now I've got 12 'Ultra bright white' LEDs mounted over the 2g; arrays were built with a radio schmuck IC board etching kit - power is being suplied by an old AT power supply. 

The LEDs I obtained were horribly blue (Looks like I'm running a SW reef in the 2g) So I got some red LEDs from radio schmuck, I'm going to add a 4 red array - even out the color a bit, with a potentiometer so I can dial in/out the red as I see fit - more red for growth, less red when I actually want to look at the fish. 

Andy

Andy L

Man created Planted Fish tanks, God created algae.


----------



## SoCalSar (Feb 4, 2003)

Nice. Sounds like the "ultra bright white" LED's look like HID's. Good idea mixing the red and white. Think you could use some sort of filter lens on the LED's to filter out the unwanted blue portion of the spectrum? Although, I don't know what you would use.


----------



## IUnknown (Feb 24, 2004)

Lot of recent discussion on Aquatic plant digest and nano-reef,

"
Here are some pictures of stuff people are doing for salt water setups.

Greg

http://www.nano-reef.com/forums/showthread.php?s=&threadid=22879

"

*Journal Database*


----------



## Gomer (Feb 2, 2004)

A couple things to consider. If you are looking for growth and not just lighting a tank (which I think we all want







)...then just any ol red or blue won't cut it. Chlorophyll A and B both have absorbtion bands that are not easily matched with LEDs (or atleast the ones I can find). Also, you NEED blue for more than just growth. Blue is what the plant uses to in order to know what direction to grow.










..everything else is wasted as far as growth is concerned.


----------



## AndyL (Jun 5, 2004)

What's the difference between chlorophyll A & B? 670nm LEDs are easy to come by - NASA and the Hygro LED guys use arrays built from 670nm and 470nm LEDs. 

Andy

Andy L

Man created Planted Fish tanks, God created algae.


----------



## AndyL (Jun 5, 2004)

Digging up an old thread - anyone interested in this lighting should take a look at:

http://reefcentral.com/forums/showthread.php?s=&threadid=337077&perpage=25&pagenumber=1

Someone there has already built a 99 white 3 blue light system - for a reef tank. Lot of tech data there too for those who can figure such things out









Lots of good stuff there!

Andy

Andy L

Man created Planted Fish tanks, God created algae.


----------



## loj04 (Aug 17, 2003)

Ha ha! Something I can actually help with, being the lowly high school student that I am. Yay for AP biology!

Anyway, chlorophyll a and b are two major classes of pigments that absorb different wavelengths of light. This is to help plants get the most energy bang for their buck of sunlight. Nothing really significant about them except that they absorb different wavelengths.

Something else to consider about the wavelength of light that you might choose. Plants are not as simple as you might think. As pointed out by Gomer, light that does not directly deal with photosynthesis still has an effect on the plants that can be quite significant. There are many systems that plants use that are dependant on different wavelengths of light. I don't mean to discourage research into this matter, but this is just a warning that you might have to try alot of things to get a good system working...

For instance, you know that when the green chlorophyll dies in the winter, it leaves this reddish orange color in the leaves. This is also a different class of pigment that deals with photosynthesis, called carotenoids (think carrots). 

These wavelenghts absorb blue and green, and thus appear yellow or orange. Carotenoids are important to plants because they protect the plants from free radicals caused by UV. I don't know if a lack of a certain wavelength will cause a decrease in these pigments, but its quite possible that some essential function might be lost if you choose a too specific wavelength.

In plants, there are two systems at work in photosynthesis called photosystem I and II that are stimulated by certain wavelengths of light, specifically for I, 700nm, and for II, 680nm. They work together as well.

For more information about photosystem I and II, look up Z scheme, and possibly Robert Hill and Fay Bendall.

What I'm trying to state is that LEDs are probably not good growing lights on their own, but I think that they could be used as supplementary to feed specific systems?


----------



## loj04 (Aug 17, 2003)

Or, one could use "full spectrum" LEDs, as I've heard that they mimic real sunlight very well. Just remember that plants are hella complicated. Trust me, I'm studyin them right now.


----------



## AndyL (Jun 5, 2004)

I've long since stopped worrying about spectrum - gsmollin posted some nice pictures of spectrum of an LED and some flourescent bulbs a little while back - definitely worth a look at. 

My 2g hex got 2 arrays of LEDs - 6 5w "Super Bright White" I believe they were 8000mcd LEDs, design error caused an early demise... But while they ran - the growth was WAY beyond what I was getting from the 2 13w PC's that are/were on the tank. 

I just ordered in some more LEDs (16000mcd) I'm re-engineering my LED arrays, and will be posting pictures probably in a month (currently we're in the process of moving - things are a bit crazy). Gomer is about to order some Luxeon III's to test on his .5g nano; I'm going to be ordering some also - to do some comparison testing on some 2.5g tanks. 

Andy

Andy L

Man created Planted Fish tanks, God created algae.


----------



## AndyL (Jun 5, 2004)

Since gomer doesn't feel the need to share his ongoing project here...

http://www.aquaticplantcentral.com/forum/viewtopic.php?t=1068&postdays=0&postorder=asc&start=30

Who was saying LEDs couldn't grow Plants?

Andy


----------



## Gomer (Feb 2, 2004)

Come on...you know you all want LED lighting









the smallest of my light setups. 3x1watt.


----------



## Chapy (May 3, 2004)

Hello all,
The lighting looks very good. I do however have a question kinda of off the path. If I just want moon light couldn't I just use a strip of blue Christmas lidhts? 

Seems to me like they would produce some low heat light. The only prob. is finding a strip small enough. Or retro fitting a fifty bulb strip. I know only as much as you have experianced at this point. 
Thanks, Chapy


----------



## Oleg (Jun 15, 2004)

> quote:
> 
> posted by AndyL:
> ...My 2g hex got 2 arrays of LEDs - 6 5w "Super Bright White" I believe they were 8000mcd LEDs
> ...I just ordered in some more LEDs (16000mcd)...


AndyL, sorry, it is not clear to me. Did you have 5W total? Or 2 arrays - 5W each? What does "6" mean?
Is 8000mcd total? Is 16000mcd total?


----------



## Gomer (Feb 2, 2004)

I believe andy had a total of six, 5mm 8000mcd LEDs.

They couldn't be 5 watts. The only 5 watters I know are luxeon Star V's.

IF 5watts, they would be drawing something like 700mA at 7volts EACH (star V's)


----------



## AndyL (Jun 5, 2004)

The arrays were setup with 6 - 5mm (3w I think - musta been a typo) 8000mcds. 

I've got the new arrays of the 16000mcds setup for the 2.5g. Working out power supply and heat issues. (Mainly, amp draw goes up as they heat up - after an hour they're over their rated current) Then I need to rework the tank so plants will grow again...

Andy


----------



## Oleg (Jun 15, 2004)

So you had 3W*6 = 18W total! This is a lot for a 2G tank!
I read that LEDs waste only 10% on heat.
Fluorescent lamps waste about 60% on heat.
(18*90/100)*100/40=40.5
It means that
18W light of LEDs = 40.5W of fluorescent light


----------



## AndyL (Jun 5, 2004)

Oleg: that may be true, in fact they're more efficient than that in a sense, because there aren't reflector losses. 

Problem with LEDs is you may need more "wattage" to cover a similar area because of the limited beam. Not as much of a problem on the bigger (and taller tanks) as it is on the small tanks.

In comparison, the 2g had 2 13w PC's on it...


----------



## Kurt Reinhart (Mar 4, 2003)

Some of you that aren't interested in DIY and want a pretty basic LED system with 5 white LEDs along an 18 inch flexible cord may now want to check out the GE product carried at Walmart. They cost ~$24. Check out this page for the details. I haven't tried one since I was hoping to spread the five bulbs along a longer length of cord.

http://www.gelcore.com/news/feature.asp


----------



## Robert Hudson (Feb 5, 2004)

Andy and others keep talking about mcd, which I have no idea what it is... but what is the kelvin of these bulbs? Kelvin is the measurement of the color spectrum or "wave length". We all know that the kelvin used in reef tanks is not what we use in freshwater plants.

So what exactly is the big attraction here for LEDs? I don't quite get it, please explain. Is it cost? Doesn't sound like it... Is it energy efficiencey? Sounds like to get the same lumen output as the 2 to 3 watt/gallon of standard flourescents that you would need an awfull lot of LEDs, so what is the reason for using these?

The link Kurt suggested states the LEDs are cool white. Cool white is somewhere around 4000 kelvin. Not what you want to grow plants


----------



## AndyL (Jun 5, 2004)

> quote:
> 
> Originally posted by Robert H:
> Andy and others keep talking about mcd, which I have no idea what it is... but what is the kelvin of these bulbs? Kelvin is the measurement of the color spectrum or "wave length". We all know that the kelvin used in reef tanks is not what we use in freshwater plants.


MCD is millicandella - 1000mcd roughly equivalent to 1 candlepower. Just another way of measuring how bright the light is.



> quote:
> 
> Originally posted by Robert H:
> So what exactly is the big attraction here for LEDs? I don't quite get it, please explain. Is it cost? Doesn't sound like it... Is it energy efficiencey? Sounds like to get the same lumen output as the 2 to 3 watt/gallon of standard flourescents that you would need an awfull lot of LEDs, so what is the reason for using these?


The big attraction of the LEDS comes from a few areas, they produce very little heat for one. Efficiency was my interest when I started looking at them, they are much more efficient at turning electricity into useable light - don't know about you but with our current electricity bills - any savings is good. Bulb replacement isn't an issue - should last for decades, unlike flourescent/PC/MH.

LED lighting is becoming a mainstay in stores/buildings, and is becoming mainstay in the automotive fields, audi is even using some for headlights! Why would we ignore looking at their use in lighting aquariums? If you think about it, they are almost perfect for our use - they're low voltage (reduces risk of shocks and 'stray voltage' in the aquarium) they produce little heat - reduces need for cooling in tanks where lights create excessive heat. And they'll last decades burned continually. (GM was saying 50 years of constantly on for its new LED tail lights in it's Cadillac). If they save us some $ on the power bill on top of that...



> quote:
> 
> Originally posted by Robert H:
> The link Kurt suggested states the LEDs are cool white. Cool white is somewhere around 4000 kelvin. Not what you want to grow plants


I haven't seen the lights Kurt mentioned, but I'm going to walmart this afternoon to take a looksee. Like any lighting, LEDs are available in basically the full range of spectral outputs, tho many aren't listed, a little digging and emailing usually will get you a spectral output graph.

Since gomer didn't post it - here's the final results of his 7w PC vs 7w LED testing:







What do these results say to you? (Full thread found at http://www.aquaticplantcentral.com/forum/viewtopic.php?t=1068&postdays=0&postorder=asc&start=0 )

Andy


----------



## Robert Hudson (Feb 5, 2004)

OK, that does sound attractive! I can tell you the biggest expense for any aquarium/pet store is cost of lights/electricity. 

But to translate it easily to the hobbyist there needs to be a common measurment of light output. The data on most flourescents available is in lumens. The watts per gallon rule is roughly based on the average lumen output of a standard flourescent. So if someone can convert the mcd to lumens, I guess that would be a big help.

What about asthetics? Can these be mounted inside a hood or canopy?


----------



## AndyL (Jun 5, 2004)

Yup, I know that only too well! At one point I had 50+ 'stock tanks' in my garage, between lighting and the linear air pump... I know the costs...

http://www.candlepowerforums.com/ubbthreads/showflat.php?Cat=&Number=521459&Main=506027 <- should help you with the translation to lumens. The Luxeon's that Gomers been using, offer lumen outputs in the 20-120 lumen per emmiter [think LED - it's lumileds terminology)

I don't think the WPG rule will ever work for LED lighting - as the problem becomes coverage more than intensity. With average beams of less than 45degrees, you really do need to plan your coverage.

But - while it does require more planning, it does allow more flexibility, instead of running 3wpg over the whole tank, you could drop to 1wpg or less for areas that are unplanted, or that you don't want plants to 'take over'. And highlight or add extra light in areas where you need it. For a shop keeper like yourself, think of it like this - you probably have some 2-3wpg systems, what if instead of lighting that whole tank, you had expandable and moveable groups of lights - instead of running say 210w of flourescent over the tank 12/7, you could put say 10w or so over each plant. So if there were only 5-6 plants in that tank, you could save power by removing / switching off the lights where they weren't needed. So instead of lighting the substrate allowing for algae growth, you're providing light only where its needed.

Another case is one I've done in the past, with flourescents, a african cichlid tank - Vals on one side of the 75, lots of sand, then rock pile on the other. Normal procedure would be to light the whole tank to 2wpg or so, I went with 36w PC over the planted end, then a pair of 15w NO to cover the unplanted end. Saves on power and reduces the likelyhood of algae growth. But future reworking becomes difficult. With LEDs, it could be possible to setup the lights to sit on a glass/plexi, then leave the lights 'mobile' so one can put them where they are needed. Adding or removing lights simply becomes an issue of plugging them in, and putting them where needed.

Driver technology isn't quite where we'd want it for the above theory, you have to plan out your lighting, but it wont be long before it is possible.

If anything the LEDs are easier to fit into a hood, rather than having 6-12" tall hoods to accomodate the lights, in theory you might be able to fit it into a 1" tall hood. Of course that would require some interesting trickery with heatsinks etc - but it is theoretically possible.

One of the neatest things about the LEDs, is that they are easily controlled by X10 control systems. As well as standard 24v controls (like what you'd see in overhead door operators, HVAC etc). Some of those playing with LED lighting right now are playing around with LED arrays of various colors, so they can adjust lighting intensity, coloring (think pink/red/purple sunsets and sunrises) light/dark periods (mimicking thunderstorms, cloudy days etc). This may be what is needed to get blooms from various types of flora, and it could be a spawning trigger for certain fauna...

Andy


----------



## Robert Hudson (Feb 5, 2004)

Well for the technology to prevail to the masses there needs to be a simple way to calculate how much light you need.

I hope you and Gomer will continue to report your findings. I will be very interested to read it!


----------



## Gomer (Feb 2, 2004)

I wanted to add a correction. LEDs are NOT these ultra high efficiency beasts that everyone seems to think they are. Everyone is pretty much use to these 1/10 (for high intensity) or even down to 1/100 watt LEDs. ..sure these will seem like they produce no heat. The reason they seem so bright is they are so directional. lumen wise, LEDs are about as efficient as incandescent bulbs (according to lumiled). The difference however is that you aren't having any reflection losses to get that other 75% of the light down to the tank...also no restrike losses. Another thing on efficiency, fluorescent lights flicker at a very high rate, meaning they aren't truely always on. LEDs are CONSTANTLY on.

The BIGGEST attraction to these guys is that these guys last forever...effectively....they also seem to grow plants pretty well


----------



## Roger Miller (Jun 19, 2004)

It seems like if LEDs are no more efficient than an incandescent light then a setup big enough to light a tank will generate a lot of heat.


Roger Miller


----------



## Gomer (Feb 2, 2004)

Gomer, you have me utterly confused.

Incandescents are terribly inefficient. The majority of the energy they emit is heat, not light. If LEDs are similarly inefficient, but they warm up less than a PC light (which is *way* more efficient than incandescent) then where does the wasted energy go?



> quote:
> 
> The heatsink my LEDs are on gets warm, but I can hold my hand on it indefinately. The PC is a much smaller heating surface, but I can't touch it for long without burning my hand.


I'm not sure what you mean. What is the "heating surface" on a PC that is smaller than a LED heat sink? If you mean the surface of the lamp, then I don't find that very suprising. The temperature difference there has more to do with the size, thermal conduction and cooling than it does with lamp efficiency.



> quote:
> 
> The PC light tank (with it's light at the same distance from the water) evaporates more water weekly than the PC setup.


 Which is evaporating more? A higher evaporation rate implies a larger energy input, but it could also mean (for example) more air circulation. I'm not sure it says anything about whether the energy input is light or heat or something else.



> quote:
> 
> Draw your own conclusions


I'm struggling to do that







.

Roger Miller


----------



## gsmollin (Feb 3, 2003)

LEDs efficacy peaks out at about 25 lumens/watt. Fluorescent lamps peak out at about 85 lumens/watt. The real difference between fluorescent and LED is that current LEDs are operating at a small fraction of their theoretical maximum efficiency, and fluorescents are operating at near their theoretical maxiumum eficiency. LED lighting is being developed at an increasing pace, and considering the significant strides made in the last 10 years, we can expect LED lighting to take over for incandescent in the near future, and take over for fluorescent in the next decade. So this is a developing area, not at all mature, and improvements in this technology will be 100 X in the next decade. Check out this FAQ:

http://lighting.sandia.gov/Xsslfaq.htm


----------



## Gomer (Feb 2, 2004)

Roger, lets try it this way. Two test tank are as alike as I can make them. Both the LED and PC setups draw about the same amount of current from the wall. THe LEDs seem to grow stuff considerably better.


with regard to evaporation, the PC setup evaporates more water. Both setups are right next to each other with NO fan cooling (ie, no air circulation affects). If one setup evaporates more, all things being equal, the light source to that tank is outputing more heat.


----------



## Roger Miller (Jun 19, 2004)

Gomer, I don't doubt your observations, but I'm having trouble getting my mind around the why and how.



> quote:
> 
> Originally posted by Gomer:
> Roger, lets try it this way. Two test tank are as alike as I can make them. Both the LED and PC setups draw about the same amount of current from the wall. THe LEDs seem to grow stuff considerably better.


I think the physics of the situation is a problem. If LEDs have an efficacy much lower than fluorescents and if both installations are drawing the same amount of power from the wall then the PC setup should produce more light than the LED setup. How is it that they 'grow stuff considerably better?' Do the ballast losses account for a lot of the PC losses, but not get counted in the efficacy? Is the PC reflector not getting light on the subject? Is the LED spectrum remarkably different from the PC spectrum?



> quote:
> 
> with regard to evaporation, the PC setup evaporates more water. Both setups are right next to each other with NO fan cooling (ie, no air circulation affects). If one setup evaporates more, all things being equal, the light source to that tank is outputing more heat.


Thanks for the clarification.
Greater evaporation means that the PC is putting more energy into the water. It doesn't mean that energy is emitted from the lamp as heat. Any light that goes into the tank either passes through, reflects out, or gets converted to some other form of energy. As far as conversions go, the vast majority of the light that gets converted to something elee is converted to heat. A light source can emit less heat but cause more evaporation just because it produces more light.

Roger Miller


----------



## bharada (Apr 17, 2004)

This is definitely an interesting topic, but it did throw me a curve when Gomer seemed to be talking to himself four posts up.







Kind of late for April fools jokes, huh Roger?


----------



## Roger Miller (Jun 19, 2004)

bharada, I screwed that up. Bad moderator







I wanted to quote Gomer's post and edited it instead. I didn't realize it until about an hour later when I couldn't figure out why the forum listed Gomer as the author of the letter.


----------



## 83mulligan (Dec 28, 2004)

OK, I've read through most of this and the conclusion seems to be that LED's can grow plants as well as flourescent if you can concentrate the light. I want to use it to focus wattage on one plant in a tank. The area will be less than 3/4 gallon and the distance from the plant to the light will be less than 8". What do I need to setup one 1 watt bulb to light this area? I'd like to order a plug it in package but am willing to diy if necessary. Do I need to build my own reflector? Help me out please, I'm ready to go.


----------

