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The myth of LED efficiency


Hydro

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OK, I know that I'm about to start WW 3 here but I think I can help clarify some things about using LED lighting for coral growth. Contrary to perception, lumen for lumen, MH lighting is considerably more efficient than LED lighting. MH lighting puts out more lumens, per watt of power, than LED by 25%. A 600 watt MH lamp, for example, creates 60,000 lumens. A 600 watt Lumatek digital ballast uses 550 watts of power. An LED fixture that creates 60,000 lumens uses 800 watts of power...it's true. The low wattage LED's out there simply do not produce as much lumens as MH . You can put a lower wattage MH and use less power too. You will still get more lumens per watt of power no matter what size bulb...but 1000 watt lamps are the most efficient.

An HPS can put out between 90-150 lumens per watt, once you add in ballast losses and reflector loss the result is 63 to 105 lumens per watt. So the lamps getting 100 lumens/ watt will produce 60,000 lumens at 600 Watts, really it is more like 660-680 watts including ballast.

An LED at temperature and continuous emission can produce about 75 Lumens per watt, or more like 68 lumens per watt including ballast. I used 75 watts per lumen as a guide. So at 800 watts time 75 lumens per watt = 60,000 lumens.

Also it is widely accepted that LED's create less heat....well this is true b/c they are consuming less power due to their lower lumen output, that is the only reason. But again if you are comparing apples to apples (lumens to lumens) LEDs actually create MORE heat. Watts equals heat whether it's your toaster, refrigerator, computer. This is the only reason why digital ballast make less heat than magnetic ballast, it's because they use less power.

This raises the question about why LED's even exist since they produce less lumens per watt. The reason is because MH lighting creates a spectrum of colors, some that can't even be seen. Plants only use a certain spectrum of light , so the unused color spectrum is wasted lumens. What they have figured out is that flowering plants use a mixture of 460 nm blue and 630 nm red for example, so they produce a LED fixture that consumes 400 watts of electricity but has comparable lumen output in only these 2 colors as a MH, this is how they claim "equal to a 600 watt MH". This also goes for commercial and residential lighting, again they are only creating visible light so they are more efficient in these instances. Let me say now that in fish only tanks, vegetative plant growth, commercial or residential lighting, LEDs are more efficient at producing the same amount of visible light for short distances.

LED's do not pack the "punch" that MH lighting has, in other words the ability for the lumens to make it to the bottom of your tank, or to penetrate a plant canopy to light lower branches. You won't see them mounted directly to a 20' high celling in a commercial building like you see MH.

The last advantage/disadvantage of LED's of that they do not produce UV. Some plants require UV light, and some don't. I don't know about corals, but fish don't require it, so in fish only tanks and to replace traditional lighting LED's are great b/c UV creates radiant heat. UV is the heat that is felt instantly on you hand when you stick it underneath a MH lamp...or even step out in the sun --not the air temperature, the warming from the light. The UV heats what it contacts and then these objects give off heat creating more heat in the environment. There are LED's available that produce UV that can be added but again you get back to the same conclusion, by the time you add these the fixture is producing heat and you are using lots of power.

Seedlings and small plants do great with the low stress of an LED to get them started but as they mature they need more lighting spectrums and some plants need UV to ripen properly. There is millions and millions of dollars spent a year studying plants, their growth, lighting and nutrition needs b/c it's a multi-billion dollar a year market that our lives depend on. Reef tanks on the other hand are a hobby that there is absolutely research being done about corals but frankly it doesn't have the funding that agriculture does. So what I'm trying to say is that YES indoor gardening of plants and fruits have benefited from LED technology, but it is b/c these LEDs are designed to be plant specific and what people don't know is that it has to be researched now how to feed the plants using LEDs instead and what temperatures the greenhouses now have to be kept b/c the lack of UV. UV makes the plants drink more and without it typically the grow rooms are kept warmer to try and maintain similar plant canopy temperature when using MH.

Here is my point....you can see how complicated this can get with all of this research needed for each type of plant to actually make them grow at the same rate using less power so can you imagine what a coral needs? What part of the spectrum of light does my red planet coral compared to my acans??? Who knows! I have 100 different kinds of corals in my tank from all over the world, do LED manufacturers claim that all of these corals use the same spectrum of light? So in order for LED's to be more efficient for coral growth it has to be determined exactly what a particular corals lighting requirements are so that only those spectrums are produced. Ok let's say they get it figure out and most corals use X nm mixed with X nm for optimal coral growth for a type of acan...is that color going to be attractive in your tank? Will that spectrum actually make the coral look cool? I can tell you the ones for flowering plants are a pink/purple color that I can't stand to be around, it's hard to adjust your eyes back to normal after being in an LED garden. What about UV? Do any or all corals use UV to grow? Do they use a little or alot? Do they use other parts of the lighting spectrum that isn't visible to us? I think there are too many corals to study individually to make LEDs viable to reef keeping as a hobby. The only viable application I could think of is for a specific coral, on a commercial scale to make it worth the cost, and not in a display.

Please understand that I'm speaking from experience, this isn't just stuff that I've read on the web. I'm also not arguing that people can keep corals alive under them and that some people are using them just fine, I'm arguing that power consumption vs. power consumption MH will win everytime in our hobby. My company is a manufacturer of cutting edge gardening equipment so LED's have been on our radar for years. We have tested $3k fixtures that plants die underneath, I have also talked with several LED manufacturers about making us an fixture that is equivalent to a 600 watt light and I finally had a company going to build for me....but the problem is that it uses 800 watts of power. I'm very well embedded in the indoor gardening industry and we are privy to the newest technologies before they are even written about online, and LED technology isn't close to replacing MH lighting....especially considering they are 10x's the price for 1/2 of the lumens. You would have to use the fixture for 5 yrs to save enough money on electricity just to pay for it. My company manufactures water-cooled lighting equipment which increases the efficiency of cooling the heat they produce by 50%...this is how we are increasing the efficiency of using MH lighting. If LEDs were the future we would be manufacturing LED's, I have tried to make it work....it just isn't going to happen. How can you duplicate the sun without any heat?

With all that said...it will be a different type of lighting that I see in our future. Plasma.

http://urbangardenmagazine.com/2010/02/plasma-grow-lights-the-promises-of-full-spectrum-plant-lighting/

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Hydro, you're right I was wrong in Thresa's thread about Stunner light strips regarding the effeciency of LEDs. We're not there yet. Dr. Joshi's research did show how far they've come though with one of the LED fixtures showing a max PAR reading per watt roughly double the Metal Halide fixture used in his comparisons and it also showed the problem with light penetration, or punch as you said, with the same fixture.

Gab, here's the link I posted last month for the Plasma LED's (which is a very different technology from what Hydro and I are talking about).

http://glassbox-desi...ches-aquariums/

For those so interested here's a link to an intriguing technology which probably will never be seen in the aquarium trade. What caught my eye was the life expectancies of 100,000 hours. A friend of mine did grow some acropora, montipora and others but with a color temperature of 4100K the colors quickly shifted to brown.

http://www.sylvania....escent/Icetron/

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Hydro,

Without asking you to repeat anything you might have already talked about on other threads, can you point me to any of your threads or other info that talks about using water cooling for MHs? I currently have 2x400W MHs and am building a new light rack that will have 3x400W MHs (plus 4X140W VHOs) and would be very interested in how I might could use water cooling to reduce heat and possibly save electricity.

Stephen

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I'm pretty sure the high wattage LEDs such as cree and luminex have an out put of 161 lumens per watt. So 800 watts at 161 lumens per watt would be 128,800 lumens? This article is over a year and half old too.

http://www.cree.com/press/press_detail.asp?i=1227101620851

here's a newer article that cree claims to achieve 200 lumen per watt.

http://reefbuilders.com/2010/02/05/cree-breaks-200-lumens-per-watt-led-efficiency-barrier/

I don't know a lot about LEDs but I've been researching and I believe you can successfully run a sps dominent tank on these high powered LEDs. I think people who are unaware of LEDs walk into the LFS and see these 30w fixtures composed of 1w garbage LEDs and buy them expecting to supplement for MH or t5. Just a big misunderstanding in my opinion.

I'm hoping to build a fixture just like this for my 30 gallon nano.

http://www.reefcentral.com/forums/showthread.php?t=1662682&page=12

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Did you get those Plasma lights yet from that video link someone posted earlier? I would love to hear and experienced unbiased opinion on their viability.

I sent them an email to them straight off of their website. I explained that we were involved in the gardening industry and that we could sell many of their fixtures as long as it worked as advertised. I never even got a response from them which told me right away that it doesn't work as advertised. Even if the technology was close it seems that they would be interested in at least talking to us. I was really hoping for some good news from them.

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Hydro,

Without asking you to repeat anything you might have already talked about on other threads, can you point me to any of your threads or other info that talks about using water cooling for MHs? I currently have 2x400W MHs and am building a new light rack that will have 3x400W MHs (plus 4X140W VHOs) and would be very interested in how I might could use water cooling to reduce heat and possibly save electricity.

Stephen

You can check out the video that Mark posted on our 440 build (several more videos on the way), that might help explain things. We have not sold to the aquarium market yet, just gardening, so far so I don't think that you will find anything online about it. If you want you can check out either of our websites www.hydroinnovations.com or www.icehousedistribution.com for videos and more info.

You are welcome to come out and see how we are water-cooling our tank, I would be glad to show you.

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I'm pretty sure the high wattage LEDs such as cree and luminex have an out put of 161 lumens per watt. So 800 watts at 161 lumens per watt would be 128,800 lumens? This article is over a year and half old too.

http://www.cree.com/...i=1227101620851

here's a newer article that cree claims to achieve 200 lumen per watt.

http://reefbuilders....ciency-barrier/

I don't know a lot about LEDs but I've been researching and I believe you can successfully run a sps dominent tank on these high powered LEDs. I think people who are unaware of LEDs walk into the LFS and see these 30w fixtures composed of 1w garbage LEDs and buy them expecting to supplement for MH or t5. Just a big misunderstanding in my opinion.

I'm hoping to build a fixture just like this for my 30 gallon nano.

http://www.reefcentr...1662682&page=12

I'm not familiar with high powered LED's and unfortunately I'm still skeptical. I would think that if they were that efficient that all LED lighting fixture manufacturers would be using them. I know that I seem pessimistic about LED's and it b/c of my experience with them, guys telling me " I have the light fixture that works" and it turns out to be a waste of time. Also you are still in the same position with not having the complete lighting spectrum, only being limited to whatever color the LED is capable of producing.

Yes you can successfully keep coral alive with LEDs I completely agree. But I don't think that you can ever expect the same amount of growth as an MH, especially for the same amount of power.

Thanks for the comments, good discussion. I wanted to post this for one reasons, oI don't want people to waste their hard earned money on LEDs, at least until they are ready which to be honest I don't think will ever happen, if they can somehow double their efficiency,create an entire spectrum of color from one fixture, increase the punch to get to the bottom of the tank, and to do all this withoug increasing the heat the already produce....

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I have an all LED tank and there is a lot of heat. I think that the heat is easily removed through finned aluminum heat sink and high powered fans. Driver box is also aluminum and has a fan. I have 30, 3w high output cree LEDs. But I have never tested any output so I can not specifically argue what I have. I can say that I have lots of different coral and it is thriving. My anemones love the lights and look better than ever. My tank temp never goes above 79.5. Even now in the summer.

Honestly, I have been wondering when you would make your pitch. As far as plants go, If I was in the indoor grow business I would buy your product. I have read a lot about you and what you make. I think you make a lot of good points. As for my 29gallon AIO. LEDs were the best price with the least needed to run and keep tank cool.

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I have an all LED tank and there is a lot of heat. I think that the heat is easily removed through finned aluminum heat sink and high powered fans. Driver box is also aluminum and has a fan. I have 30, 3w high output cree LEDs. But I have never tested any output so I can not specifically argue what I have. I can say that I have lots of different coral and it is thriving. My anemones love the lights and look better than ever. My tank temp never goes above 79.5. Even now in the summer.

Honestly, I have been wondering when you would make your pitch. As far as plants go, If I was in the indoor grow business I would buy your product. I have read a lot about you and what you make. I think you make a lot of good points. As for my 29gallon AIO. LEDs were the best price with the least needed to run and keep tank cool.

Thanks for the comment.

If you don't mind please post a pick of your lights and corals, I would like to see them. Hope you don't mind a couple of questions...how many colors are there in the fixture? Have you used MH lighting before and compared growth? How much power does your fixture use?

What I would be impressed with is a side by side comparision if anyone is up to it. It would be great to see coral growth and color in a controlled test. I have run these tests with plants before and it was a failure, that's why I'm not interested in doing this again. When you say thriving do you mean significant growth or does it just stay alive? How are the colors of your corals when compared to the same coral in other peoples tank? If you send a pic you can tell us all what you have in there so that we have a baseline of comparsion.

Well this wasn't really a pitch...my 440 gallon water-cooled tank is my pitch:) . No this came about b/c I just recently spent time with another LED manufacturer, the most honest one that I have worked with yet, but it didn't work out b/c of the power draw. If I put plants under this LED they would grow like crazy, just like a MH, unfortunately it used more power than a MH. Also I see things written about LEDs that I don't beleive in the gardening world and with aquariums and I don't want people to get sucked in too quickly. I'm glad that it is working for you, I wish that you had used a MH on that tank before installing the LED so that you could truly compare the difference.

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This is coming up alot lately on the forums. The new LEDs have a very strong following it seems but from a business stand point I dont see them taking off. I think plasma may have a chance but we will see. Here is why I say LEDs are at a disadvantage-PFOs rights to LEDs being used for aquarium use. For another company to take them on in court they would rack up some fees plus if they won they would already be out that money while the competition could move in. The businesses wont make as much money selling bulbs. The long life on LEDs make them alot less profitable as the bulbs dont need to be replaced nearly as often. This is why alot of diyers are making there own fixtures from the high output LEDs with reflectors that suit their tank. I just dont see a manufacturer putting out a lower cost product(as there are some products out there already) anytime soon.

Hydro- I didnt know you manufactured all that for gardening also. Im going to have to look more at your website.(I graduated with an Ag. degree last august.)

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What I would be impressed with is a side by side comparision if anyone is up to it. It would be great to see coral growth and color in a controlled test. . . . When you say thriving do you mean significant growth or does it just stay alive? How are the colors of your corals when compared to the same coral in other peoples tank? If you send a pic you can tell us all what you have in there so that we have a baseline of comparsion.

Do you have the space to set up multiple tanks? I'd love to do a long term comparison like Dr. Joshi did with Metal Halides and T5s and reported in Advance Aquarist.

http://www.advanceda...08/3/aafeature1

What's intriguing is some corals showed better growth under T5's than Metal Halide.

Considering how much color can vary with the same species in the same tank I'd think pictures with a ruler showing growth over time is a better judge of how a reef system is performing. What we really need is simple and easy way to show the entire light spectrum and intensity that a coral colony is getting. Websites like Advanced Aquarist and others are incredibly helpfull in thier reviews of bulbs and fixtures but there's still too often an element of guesswork when trying to match conditions to maintain a specific color for some corals or the best growth rate.

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First, let me say this. I'm not an expert in lighting systems, but I am a scientist and I can do research.

I would suggest this page: Aquarium Lighting

It gives an in-depth discussion of all factors of aquarium (both fresh and salt) lighting and the descriptions of various lighting methods. This is the main reason that I chose to go with LEDs.

Now, with my LED set-up, I've got 2 30-Watt white LED spots (running at roughly 18,000K). There are 14 3-Watt whites (6500K) and 14 3-Watt actinics (420 nanometers). The 420s and the 6500Ks are EXACTLY what photosynthetic organisms (all of them) need. There's not a whole lot of variation in photosynthetic organisms, that's what they need. The 18,000Ks are for the looks.

I can only tell you my experience with LEDs as I've never run MH. I love the LEDs. The whole unit is cool to the touch all the time.

When I had a 96W power compact lamp, I was given a small frag of birdsnest SPS. It did OK at the very top of the tank, it maybe doubled in length in 4 months. I put in 160W LEDS and moved the birds nest to the bottom of the tank, it has still grown like gangbusters. Like so:

December (acquisition of birds nest under PCs)

post-981-090366000 1277262705_thumb.jpg

January (still PCs) (upper middle right, next to the intake tube)

post-981-039555900 1277262845_thumb.jpg

March (aqusition of LEDs) - this pic was the day after I got the LEDs, so no real influence of LEDs yet

post-981-047389200 1277262911_thumb.jpg

Sometime in May (LEDs and moved to the bottom of the tank)

post-981-075001000 1277263023_thumb.jpg

Since then, I've added some really nice, heavy lighting requirement corals and they are doing fine under the LEDs. Added bonus, I won't have to even think about changing light bulbs for another 12 months. They say 5 years, but I'm being conservative and planning to upgrade half the lamps in 8 months or so and the rest about this time next year. I'll be upgrading them to the same wattage, but higher lumen units.

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I'm no expert on lighting but I did do some research when I decided to go LED. It's my understanding that PAR is more important than lumens. In other words, you could have high lumens and low PAR and have problems. Is this not the case? Someone care to explain?

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My understanding is that you could have a million lumens and photosynthetic organisms can still starve. The light must be in the correct wavelengths.

Consider the following:

post-981-030370700 1277329960_thumb.jpg

This diagram (taken from here: Photosynthesis and light wavelengths) shows that photosynthesis is greatest in the 420-460nm (nanometers) wavelengths, with another strong peak at 660-68nm. The top graph shows that at 420 and 680, almost 100% of incoming light is absorbed (by different chlorophyll molecules). Between about 520nm and 660nm less than 50% of the light hitting the organism is absorbed (this would be why plants look 'green' as green is 492nm to 577nm).

So 50% of the energy of any bulb that puts out green light is wasted... as far as photosynthesis is concerned. In terms of MH lamps, that's wasted energy and wasted heat for no real reason.

The OP is correct in that LEDs generally generate a very specific frequency of light (same thing with an actinic T-5 or PC bulb). However, the ability to place many different LED and varying (and photosynthetically important) wavelengths give it a slight advantage (IMHO) over MH.

So, a very well designed LED fixture with multiple lamps mostly in the 420-460nm range and the 660-680nm range will provide the best possible lighting for the organism. Other lighting may be required to make you think the tank is pretty. Those 15,000K - 20,000K bulbs for example, produce a beautiful effect in the tank for us, but aren't really all that different for the organisms than a 6500K bulb.

Check this graph out:

post-981-030822300 1277330623_thumb.png

OK, this is really more about blackbody radiation, but the center of the colored area has a line that shows how the Kelvin (K) temperature rating of a blackbody (light bulb is close enough for our purposes) relates to the color of light (the line around the outside of the colored area shows the wavelength).

You can see that anything about about 6500K is mostly blue, which is what drives photosynthesis anyway.

I hope that helps a little.

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Very good info, thanks.

My biggest complaint is the efficiency, I think that a head to head competition would be awesome and can settle this stuff once and for all....I think. I'm no scientist just an end user with some hands on experience, I agree that on paper LEDs make total sense but in real world expeirences they haven't for me. I agree with you that corals can be grown using LEDs, I just don't think that with watt per watt of power consumed that you will get as much bang for your buck with LEDs as with MH....call me crazy. I also don't think that you will get the same coloration of the coral either.

I'm curious, what nm do corals use to produce zooxanthellae? Is it the same nm that they use for photosynthesis? Is it the same for each coral? I think that there is so much more to consider than photosynthesis when it comes growth and color. I can change my lamps for 6500k bulbs and grow my corals faster but they will lose their color b/c it doesn't have the proper spectrum for optimal color, which is why I don't use them. How do you pin point what part of the spectrum that produces the best zooxanthellae for each different kind of coral?

Its hard for me to compare the growth of my corals against yours since we have completely different setups. Using the pics you posted for an example I know my corals grow much faster than that but I'm using far more power so that isn't a fair comparison. I would like to truly compare apples to apples here so I think that a side by side comparison would be awesome. I don't think that it would take more than 8 weeks to know what the results would be.

I can supply a nano cube, 150 watt ballast, 150 watt lamp, reflector and 2 large coral frags (one for each tank). They would need to be setup sharing the same water though so water quality can't affect them differently. Anyone interested?

I have another idea, what if I took some pics of an SPS frag that has been growing in my tank and placed it in your tank for 8 weeks. We can see if it maintains an attractive color and remains healthy. I know that you have had success with the birdsnest I wonder if other corals will have the same success. I think that this would be an interesting experiment if you are willing.

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I'm no expert on lighting but I did do some research when I decided to go LED.

Are you using LEDs to grow corals in your tank? Any SPS? How much LED wattage do you have overall?

Please post some pics!

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