The myth of LED efficiency

[OgreMkV]

Hydro,

The information above is for all photosynthetic organisms. Whether it's a pine tree, photosynthetic bacteria, or corals (the symbiotic parts at least), they all use chlorophyll alpha and chlorophyll beta, some also use Beta carotene, but that's another story and really more about the chemical precursors to the chlorophyll compounds.

That being said, I'm sure that some organisms may have more of one type of chlorophyll than another organism, but the 420-460nm and 680nm is really best for anything that's photosynthetic.

As far as the first experiment goes, I just don't have room for another tank (rental house here), but I'd be willing to take a coral frag for a period of time. There's so many difference though, that the test results would be basically meaningless. Feeding schedule, other nutrients in the water, I even have a pair of stupid clown gobies that like to sit in SPSs and may harass them. One possibbility would be to take your nano cube and put a piece of black PVC down the middle and put an LED on one side and a MH on the other.

Count me in as an experimenter.

To remove as much of the uncertainty as possible, we'd need to get all shots using a single camera. (I'll volunteer my Nikon point and shoot, it's good for this sort of thing) and we'd both have to do initial chemistry checks (as much as possible) and a PAR meter would be really helpful. Otherwise, we'd need to do the water checks every few days and keep a log along with pics.

There are a few potential areas of concern: the afore mentioned gobies and the fact that I have a difficult time keeping calcium above 300. Magnesium is good, but calcium stays low for some reason.

[+Hydro]

Cool sounds fun, I'm glad you are on board. I just put in a refugium on my big tank, I could put LED over 1/2 and MH over the other 1/2. Now I have to buy another LED fixture ******, how much did yours cost? If I'm comparing MH to LED we have to decide what is apples to apples before we get started...in other words what wattage of LED is supposed to be comprable to 150 MH? This is an important # and must be widely accepted for this experiment to work. In my industry they claim to use 1/2 of the power of MH. A digital ballast for a 150 watt lamp uses about 1.25 amps, so we would need to make an LED fixture that used .625 if using the example from my industry. How do we find out what is comprable?

[OgreMkV]

I've heard way too many different figures for the comparioson between LEDs and MH. I'd say that a light meter would be the better choice, rather than an estimate like that. Maybe a camera shop would loan a light meter or let us test fixtures there? A PAR meter would be even better, that would let us compare apples to apples. Let me see if I can find something research like...

My LED fixture was about $400. It's a maxspect G1 160W fixture. The G1s have been replaced with G2s, but the wattage is comparable, the G2s just use better LEDs and have moon lights.

We'd also need to consider placement depth as that's an important part of available light and the photo period.

I don't have anything but a display tank, so the frag would have to go in that. I'm running 8 hours at full power, then another hour (30 min morning and evening) with 54W of actinics only.

[OgreMkV]

Quantitative comparison of lighting systems

Try this...

P.S. You're welcome to come over sometime and take a look at my lights. I won't be home this weekend, but shoutd be available anytime after that and we're hosting the September ARC meeting.

Edited June 24, 2010 by OgreMkV

[ramsey]

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!

I just got and set up my LED system about a week ago. They are 90w ( I think) each and I have four modules total over a 175g (Aqua Illumination fixtures). I have one SPS (a monti). Everything seems to be responding VERY WELL to the new lights. There seem to be more polyps on the monit out and all my LPS seems to be opening up more and just looks "healthier". It's important to note that the light system I had before was very underpowered (1 250w MH and a 4' PC fixture), Time will tell. My point was, from what I've read, PAR is a more important measurement than lumens. Lumens simply refer to how bright our eyes perceive the light to be. I'm in no way, shape or form saying that PAR is the end all, be all. I'm saying it's a better measurement and that lumen is somewhat of a moot point. *If* this is true, I encourage you to look at the PAR data for the AI LED module in this link:

http://www.advancedaquarist.com/2010/5/aafeature2

Make sure you look at the Aqua Illumination data and not the other cheesy LED fixtures.

Then, compare it to the PAR data for some various MH lights in this link:

http://www.advancedaquarist.com/2010/2/aafeature2

Again, this assumes that PAR data is a decent measurement when it comes to growing coral. There are other measurements that may or may not be better but PAR seems to be one of the first thing the experts look at.

[ramsey]

Cool sounds fun, I'm glad you are on board. I just put in a refugium on my big tank, I could put LED over 1/2 and MH over the other 1/2. Now I have to buy another LED fixture ******, how much did yours cost? If I'm comparing MH to LED we have to decide what is apples to apples before we get started...in other words what wattage of LED is supposed to be comprable to 150 MH? This is an important # and must be widely accepted for this experiment to work. In my industry they claim to use 1/2 of the power of MH. A digital ballast for a 150 watt lamp uses about 1.25 amps, so we would need to make an LED fixture that used .625 if using the example from my industry. How do we find out what is comprable?

That's not easy to answer. There are a lot of variables that go into that. First, from my research, it seems that quality optics are just as important as the LED's themselves. There are currently two methods, high intensity, high wattage LEDs -or- lower wattage LEDs and high quality lenses. From what I can see, the second approach seems to be the best. So the real question is, do you want to compare a high quality LED fixture VS a high quality MH lamp? If you try and compare a low quality LED, nothing will get proven IMO. Again, I'm no light expert, this is based off the brief research I did when I decided to go LED. LED VS MH was a huge concern for me so I wanted to know a little bit about what I was getting myself in to.

If I could, I would love to see a comparison of an AI fixture over a 10g nano and 250w MH with a quality reflector over an exact 10g nano, both plumbed together with the exact water flow, temp, etc, etc. I think that would be a somewhat accurate comparison though I wouldn't submit it to a scientific journal. It be more of a fun pseudo experiment.

Edited June 24, 2010 by ramsey

[+Hydro]

Well I've been thinking and I can't start another project/experiment over here. I have my hands full with the big tank at this point and I need to use my refugium for a refugium. But if someone is still interested I actually have a 150 watt setup with a 30 gallon frag tank, overflow, sump, pump and the coral to test! Someone would need to supply the $400 fixture and take care of the tank....

Keep in mind that my main complaint is efficiency....take a look at the bottom of this article that was posted earlier.

http://www.advanceda...10/5/aafeature2

The aquaillumination fixtures uses 75 watts and is a 12" x 12" square,this is the fixture that shows the best results when tested. Because of the small footprint of the directional LED lighting if I wanted to use this fixture to grow coral over a 150 gallon tank (2' x 6' long) I would need 12 of them for complete coverage of the tank, the same coverage that I would get from MH. Well added up this is 900 watts...that's more than a 1000 watt lamp!!! Ok lets say you only use 6 fixtures instead only placing them down the center of the tank, that's still 450 watts WHICH IS THE SAME POWER USAGE OF DUAL 250 WATT LAMPS! Where are the energy savings? If you think that 12 or even 6 of the LED fixtures don't make heat as much heat as MH that simply isn't true, remember wattage = heat. Now the big question is will 12 of these fixtures out perform a 1000 watt lamp? Will 6 of these out perform a dual 250 watt? Keep in mind that is just to be equal power usage, the advantage of LEDs is that they use LESS power for the same results. So if you think that (3) of these LED fixtures will out perform a dual 250 watt setup I think there is no way just b/c of the small foot print alone.

[+Hydro]

ohh and to buy a 6 light fixture the cost is $3,600 and of course 12 would be over $7k dollars. You could buy lots of electricity with the $6,000 you would save with (3) 400's MH instead....and you would be using the same amount of power.

[Timfish]

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?

You hit the nail on the head with these questions! This is a major frustration for me which is why in a previous post I lamented about not having an easy way to measure the full spectrum and intensity a coral colony is receiving. An example are two birdsnest colonies in one of my tanks. They are from the same parent colony,are at the same depth and are 6 - 7 inches apart and are two different colors, one is orangeish pink the other is purple. The lights above them are 250W HQI in Lumenmax reflectors with lumatek ballasts. Light one is a Ushio 14,000K (tests as 12,000K in review on Advance Aquarist). 2nd is a Phoneix 14,000K third is a Phoneix 20,000K. A sister colony from the same parent in a different tank under the same Ushio 14,000K is a beautiful pastel pink. If I could measure the spectrum I could manipulate it to get the color I want.

[Timfish]

Definitely count me in on this. I'm pretty sure I can swing the cost of the LED fixture. I think we need to match wattages myself if Hydro has a 150W fixture we should get a 150W LED setup. I'm also not adverse to getting a LED fixture that is rated at the same lumens as Hydro's fixture instead just I'd be inclined to go with wattages first. I personally think we need to look at bigger tanks. As Hydro has pointed out and Dr. Joshi's research has shown penetration or "punch" is an issue and I would want to be able to measure intensity ideally under water 2' and 3' below the fixture.

Like Hydro I don't have any space for another project. I'm also working on two that I need to finish before the end of July so I wouldn't have a whole lot of time to mess with this much until then. I would also like to try as many species as we can possibly fit in the tanks.

I've posted these previously but I'll do it again here since we're trying to something similar to these two experiments:

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

http://www.advanceda...10/2/aafeature2

As far as measuring the light, I have a Lux meter with blue, green and red dichromatic lenses. Ideally somebody out there has something better.

[Timfish]

And if this system is north I could do the maintenance.

[Will]

as OgreMKV said before with his discussion of Chlorophyll A & B, you only need to target the blue and red WL in order to get adequate photosynthesis, however adequate photosynthesis does not equal good color. Saying that, all photosynthetic organisms molecular structure of chlorophyll is fairly constant, the same WL would work on all of them. However this does not correlate with ascetically pleasing coloration (created by other pigments within the tissue, also the reason why you can grow coral under 5500k bulbs, and have extremely high growth rates). also remember that the color you are seeing when you view a coral is due the fact that those wavelengths are not being absorbed, so only targeting wavelengths that provide good color (led) would stunt growth.

info on photosynthesis

http://photoscience.la.asu.edu/photosyn/education/photointro.html

[Timfish]

Even though photosynthesis is only using the blue and red parts of the spectrum I don't see a problem with looking at the green. There are florescing pigments in corals that absorb light in the green and are reemiting it.

[OgreMkV]

Even though photosynthesis is only using the blue and red parts of the spectrum I don't see a problem with looking at the green. There are florescing pigments in corals that absorb light in the green and are reemiting it.

Yes, but those do not impact photosynthesis except in a very minor way (less than 50% absorption), most is reflected.

As will said, there are two things to consider:

Photosynthesis

and

Aesthetics

There are different requirements for each.

Hydro, did you read the article i posted (and I think someone else reposted)?

The LED has 2/3rds the PAR at only 1/3rd the power.

Cost wise, a new MH bulb every 6 months ($75 or so a pop), a reflector ($150-$250), the ballast ($150 or so). I think LEDs are pretty comparable price wise, even if you have to replace the lamps every 18 months or so (between $3 and $8 per, but that price is coming down quickly). Plus there are the environmental costs.

Anyway, I've said my piece. I think LEDs are quite comparable to MH and slightly edge out T5s and are way better than PCs.

[+Hydro]

Thanks for your comments. I really appreciate hearing everyones opinion, especially those that have LEDs.

I want to have everyone out on July 10th to show off my new tank, will you guys be able to make it? I think that it would be a good time to talk about this experiment and see if we can track somebody down to take care of it. The tank party will be at my office in Bastrop and we will supply some BBQ and beers. I really want to try this b/c it seems like a pretty straight forward experiment and would answer some questions for all of us. Sounds like if Timfish will buy the LED then I can supply everything else that is needed...except someone to take care of it. I even have a small chiller to maintain water temp so that there is just one less variable in the experiment.

[ramsey]

Well I've been thinking and I can't start another project/experiment over here. I have my hands full with the big tank at this point and I need to use my refugium for a refugium. But if someone is still interested I actually have a 150 watt setup with a 30 gallon frag tank, overflow, sump, pump and the coral to test! Someone would need to supply the $400 fixture and take care of the tank....

Keep in mind that my main complaint is efficiency....take a look at the bottom of this article that was posted earlier.

http://www.advanceda...10/5/aafeature2

The aquaillumination fixtures uses 75 watts and is a 12" x 12" square,this is the fixture that shows the best results when tested. Because of the small footprint of the directional LED lighting if I wanted to use this fixture to grow coral over a 150 gallon tank (2' x 6' long) I would need 12 of them for complete coverage of the tank, the same coverage that I would get from MH. Well added up this is 900 watts...that's more than a 1000 watt lamp!!! Ok lets say you only use 6 fixtures instead only placing them down the center of the tank, that's still 450 watts WHICH IS THE SAME POWER USAGE OF DUAL 250 WATT LAMPS! Where are the energy savings? If you think that 12 or even 6 of the LED fixtures don't make heat as much heat as MH that simply isn't true, remember wattage = heat. Now the big question is will 12 of these fixtures out perform a 1000 watt lamp? Will 6 of these out perform a dual 250 watt? Keep in mind that is just to be equal power usage, the advantage of LEDs is that they use LESS power for the same results. So if you think that (3) of these LED fixtures will out perform a dual 250 watt setup I think there is no way just b/c of the small foot print alone.

I have four modules on a 6' long bowfront (two foot wide in the center). I have them hung over the tank about 4-5". The light coverage is great. I don't get any spot lighting or anything. I'm not sure why you'd think you would need 12. I wouldn't put 12 250w mh lamps over my tank. I had a 250w fixture over the tank before going to these. One seems every bit as bright as the 250w light, IMO much brighter. I'd like to get my hands on a PAR meter to test for myself. My point is, I can easily get away with four over my tank. Before I decided going with LEDs, I was gonna do a 400w MH and 2 - 250w MH's with at least two actinic T5s. I was also going to have to run a chiller. So in my case, I'm using far less wattage then I would be using if I had not gone with LEDs. Saying that there's no way of 3 of those fixtures will not outperform 2 250w MH is wrong. I think 3 would GREATLY outperform 2 250w MH's, pretty sure it would greatly outperform 3 - 250w MH's. Now if you wanted to argue if they'd outperform 3 400w MH, you may have a valid concern/argument.

[+Hydro]

Well the reason that I mentioned using 12 is b/c in the article that was posted Sanjay said that the light was very focused with the Aquaillumination fixture, from what I understood from that there would be a small footprint. OK so 12 is excessive but Aquaillumination does recommend 6 of these fixtures for a tank that size. Here is the link to the fixture they have for sale....for $4k. If AI thought that 3 of these fixtures would be sufficient they would sell 3 for a tank this size, obviously the price would be much less and more people would buy.

http://www.fishnreef...r/prod_988.html

This is the product description...

LED light system complete with external controller, mounting legs, external power supply and active cooling system. Each 12" section consists of 24 LED lamps grouped into a bank of 8 lenses or pods each containing two 6500K Daylight LED lamps and one Blue LED lamp. Blue LED lamps peak at 460nm. Recommended Tank Width: up to 24". Recommended Tank Depth: up to 36" with carefully planned placement of corals. Power Consumption: up to 100W per 12". Warranty: 2 Year. (1 Year on Power Supply.)

I thought this was interesting...

Recommended Tank Depth: up to 36" with carefully planned placement of corals.

I thought this was very interesting....

Power Consumption: up to 100W per 12"

That means that this fixture draws 600 watts of power!!! And this is the fixture that Sanjay said performed well! AGAIN where are the energy savings! Please note that these guys are the professionals and know much more than ANY of us on these forums when it comes to LEDs, if they thought that 1/2 the amount of LEDs would perform well in a reef tank they would sell a 3 light fixture for a 72" tank. PLEASE NOTE THAT A 1000 WATT LUMATEK BALLAST USES 750 WATTS!!! Here's the deal, they are basing these figures off of old magnetic ballasts and are not considering the more efficienct digital ballasts that have been available for years

I know that 12 might seem excessive but I was running 1200 watts over a 175 and my corals LOVED it, if I were experimenting with LEDs I would have to go with a 12 light fixture (or (2) 6 lights). I want my lighting to be intense b/c I want my corals to grow as much as they can. My thinking is that whether you have 100 corals or one, or if you can grow them 1/4" a month or 1" a month, tank maintenance is still the same no matter what, it only costs more in electricity. But I never would have used these LEDs b/c with 12 I would be using more power (1500 watts) than the (3) 400 watts over my tank which was consuming about just under 1000 watts of power.

The info that I don't see is how much heat they produce. There should be a BTU rating posted if its such a low heat producing fixture...instead of 1/2 the heat....because they also say 1/2 the power which isn't true. If I were selling a fixture that made 50% less BTU I would have those specs all over my advertisements. BTW a 1000 light emits 3500 BTU of heat per hour.

I'm not sure how much better I can state my case than this.

[+Hydro]

OK lets say I agree that LEDs save energy, with cooling cost, arguable light energy savings, and bulb replacement of MH. How much a month can you actually save. My 175 tank uses about $40 worth of power a month at most. That's 1200 watts of MH lighting, 1/4 hp chiller, and all of the pumps. Lets say I agree that LEDs will save you 50% over MH, ok so you save $20 a month plus $5 a month in bulb replacement. I think that I'm being very generous with all of the figures in benefit of LEDs.

That's $300 woth of energy savings a year. The cost of the LED if bought and not homemade for a tank my size is $4k. It would take more than 10 years for this fixture to pay for itself. People say "I don't have to run a chiller", ok how is that a benefit? If you are purchasing expensive LEDs then you have the money to purchase a chiller and to pay for the energy usage for YEARS to run it and still spend less than with LEDs. LEDs are not an efficient way to spend your money either!

[Will]

just saw this same thread on RC, didn't have time to read it, any new points raised, insightful breakthroughs?

[Timfish]

Free Food?!! I'll be there!

[+Hydro]

Free Food?!! I'll be there!

[ramsey]

First, as I mentioned, I have four over my tank and the light spread is just fine. The specs you listed are for an older generation. They now recommend one every 30" or less. This is because they are using different lenses.

"Recommended Tank Width: up to 30" with proper placement of corals. Recommended Tank Depth: up to 36" with proper placement of corals. Power Consumption: up to 75W per module."

Of course they say "with proper placement of corals". You wouldn't want to put your lower light corals way up in the tank and SPS at the bottom. I have two clams at the bottom of my tank. They seem to be doing great so far. I'll keep you posted though.

Also, $5 a month for bulb changes? What kind of bulbs are you using? You said 1200w so I assume you're using 3 X 400w lights. You may be able to change one bulb for $5 per month. That's if you're using low end bulbs and your not supplementing with VHO's or T5's.

A chiller is a HUGE turn off for me. First, I have this ugly thing sitting next to my tank but the real reason is it's a piece of equipment that I MUST have. I could get by without a protein skimmer, an ATO, etc. I would not be able to get away with no chiller.

I will give you one thing, for your tank, you may need 5 or 6. I get good coverage but I also have nothing about 4-5" on each side of the tank. With my overflows in each corner, I have very little room. However, the corners of the tank are till lit on the bottom, but there is a darn "triangle" that starts about 8" up and goes about 4-5" on each side (at the top).

One more thing I'd like to mention. One of the current themes in this hobby seems to be over-lighting a tank. While I think intense lighting is important, I think it is possible to overdo it. Running 12 of these would be a waste IMO. There is a thread on MAAST that I've been commenting in and one guy is running 8 fixtures over his tank.

I will keep updated on how things are doing. I bought an acro SPS a few days ago partly due to this thread. I'm more of a zoa/LPS guy but I want to see how it does under my lights. So far, everything seems to be responding great. The true test will be growth so time will tell.

[Teresa]

I have a question regarding LEDS and the light spectrum. I'll ask the question first and then give you the background - I'm interested to know what people think or would recommend. Question: Does any blue LED put out light at 460nm? For example, can I buy the R2 Moonlight with 5 blue LEDS and get the proper wavelength for photosynthesis?

The reason I ask is because I currently have a 70w MH on my 12 gallon jbj nano cube. The light is a 10k and while I am seeing growth in my corals, I am not seeing the colors I'd like (didn't know about the k variations when I first bought the lamp). Does the MH already put out 460nm? I've heard a 14k or 20k bulb has a "more blue tint" - does this mean it has more output at the 460nm wavelength? I am considering getting the R2 moonlight and attaching it to my MH fixture. The goal is to use this light during the day so I can see an increase in the color variation in my corals (right now, most items are brown). Will this work? Is this necessary? Should I just buy a new 70w bulb at 14 or 20k?

I hope this question makes sense. I am unfamiliar with the proper wavelength terminology, etc., so I might have mixed a few things up. Can anyone help clarify?

[Timfish]

. . . Question: Does any blue LED put out light at 460nm? For example, can I buy the R2 Moonlight with 5 blue LEDS and get the proper wavelength for photosynthesis? . . .

Short answer is yes it would help with photosynthesis in conjunction with your MH but you probably want to look for LEDs that put out 420nm which is better for photosysnthesis.

. . . Does the MH already put out 460nm? I've heard a 14k or 20k bulb has a "more blue tint" - does this mean it has more output at the 460nm wavelength? . . .

Yes your MH certainly has some output at 460 but if you could find a spectral output graph for your bulb it would most likely show more output in the 420nm range. 14K and 20K bulbs look bluer than 10K or 12K because they have LESS light output through the rest of the spectrum. They are not putting significantly more blue light than lower color temperature bulbs. I have measured with a LUX meter the output on my fixtures and a 20K bulb is putting out 1/2 to 1/3 less light than 14K bulbs. I have also measured differences in output of 40% between 14K bulbs of the same wattage from different manufacters with the same fixture & ballast.

Lighting is a very complex issue. What I lament is there is no easy way for us hobbyists to get a spectral output chart of a bulb on our tanks. I know Advanced Aquarist has some good articles on lighting and bulb reviews and I've seen some posts referencing websites that looked good. If it's any consolation I've been trying to get my head around this for 23 years

[caferacermike]

Teresa I think Timfish did a great job with the help on the lights. You should have tremendous growth from a 10K bulb. Most folks see a drop off in growth as they switch to 20k but the lights help "create" the bright colors some want in their tanks. Personally I don't feel that the color of the bulbs really help color our corals. No I think clean water and the correct trace elements help with keeping corals happy. Now to avoid arguments later, sure bulbs play some sort of role in this it's just that I feel that there are a lot of other factors that play into coloring up corals than just light.

I'll toss out 1 example. You go to a fish store that displays corals under 20K, a lot do to artificially bring out colors. You take it home and put it in your tank with 10k's. They instantly look different don't they? I bet they didn't color shift in the bag on the ride home. It's just that the 20'ks are blocking out the spectrums that dull down some colors and make the rest "pop". So you can see that the 20k's weren't actually "coloring" up the corals or they would look the same at your house for a few days at least.