Holy LED light Hood Batman. Solaris.

[oct2274]

wow, now this was informative. Don't worry about bean, he'll pick apart pretty much anything. He is too smart! It truely sounds like you have a very good understanding of lighting. With a possible few corrections/clarifications this would be a pretty good sticky for the lighting forums. Thanks for taking the time to post this.

Originally posted by jcltok
I am not a physicist, but as a manufacturer of LED lighting, I can respond to your statements and questions.

1. LED provides a more precise light source than any other. The reason is that the LED is design to provide a vary narrow wavelength of light.

2. All current LEDs have a dip in the 475nm spectrum. Simply LED manufacturers have not found a precise phosphor for that spectrum range.

3. You seem to confuse PAR with light output. They related but not the same. Light output is based on lumen and can be measured by a lux meter and then converted to lumen. You can also use a lumen meter to measure if the instrument has that function.

4. PAR has been used in reef lights because of research by Ryther at Woods Hole Oceanographic on plankton showing the lighting needs of the plankton algae which happen to be the same species of the symbiotic algae found in stony corals. PAR, measured with a quantum meter, should measure the output of evenly distributed 400nm to 700 nm wavelengths. PAR has been manipulated as you state. Many MH manufacturers add exceptional amounts of violet/blue phosphors at the expense (lack) of other wavelengths, to manipulate the quantum/PAR meter into reading higher PAR.

5. PAR manipulation success depends heavily on the ignorance of users and their unwillingness to publish even their manipulated PAR results. Why? Because sea water level PAR should be about 1700 microMols/m2/sec and the manipulators are putting out maybe 300 or 600 PAR. The PAR of LEDs can also be manipulated by adding more blue color LEDs and minimizing the count of white LEDs. The same logic applies to adding phosphors to MH to manipulate PAR. That is why you see deep blue but very low light LED fixtures. The trade off is lower manufacturing costs, higher Kelvin ratings and faint light.

6. Lumen out put at sea level is 2600 lumen per square foot or 18 lumen per square inch. Lumen and PAR should be measured at the water level, and not at the source. The reason is that light output is inversely proportional to the distance it travels - the farther the light is, the dimmer it is. So high lumen - brightness is necessary. MH will reduce their light output and change spectrum very quickly which is why they should be replaced every six/eight months. LEDs if kept at proper operating temperatures, do not change lumen or spectrum until after 30,000 hours - assuming you buy the best product.


7. Kelvin ratings are a measure of COLOR COORDINATE TEMPERATUREs which can be measured by instrumentation. Higher Kelvin does not mean better PAR. Higher KELVIN means bluer light. Why is this relevant? Because corals grow at different depths and some grow in the violet/blue light - hobbyists think that is what they need and it looks cool! Unfortunately many corals live in a higher water level and do not get the spectrum they need. Also actinics make corals fluoresce and therefore leads people to bluer lights.

8. You state you are frustrated by efficiency claims. You are correct in that when you have not been provided full information, every thing else is suspect. Some LEDs are very efficient at taking one watt and making more light - therefore the efficiency claim. Notice I state SOME - since that is not all manufacturers. What really matters is the total lumen output, PAR measured correctly, power supply efficiency and so on. Then you can decide whether one light source provide the results you need for a given watt rating.

9. I have not seen your analysis of efficiency/output of LED vs MH. But, the proportions are likely close - you are basically correct in your conclusion. MHs are very inefficient as are fluorescents.

10. Spectral graphs are provide in "relative output" - in other words the proportion of one wavelength in comparison to others. In high Kelvin MH you see a huge spike in blue and minimal in the rest of the spectrum. In LEDS, you can expect a spike in the blue, a dip in the 475nm range, a rise in the 500nm tapering off to near infrared. (700nm). LEDs are not the perfect solution either - they happen to be better than MH and Fluorescents. Keep in mind that what I have stated above assumes the best LED available and not just any LED. I have not stated which LED is best on the basis of published data because that is not appropriate in this forum! I can be reached at jcltok@cox.net

[BeanAnimal]

I just don't have the energy to go through the post and make corrections or comments... This whole subject is getting kind of tiresome.

It will be nice to see the results of tests on the new generation of products... until that time...

[MorandiWine]

To be honest with you, I have not read the entire thread so if I make a statement that was covered please excuse me.

We have a Solaris H4 series working at my business and I have sold a fair number of units to customers. Everyone that has bought a unit from my store has had nothing but good things to say. Keep in mind that half of these people we setting up their first reef and the remainder had had reefs in the past and were upgrading the lighting to the LED from MH, T5 and PC systems.

My personal observations are the following:

- Growth rates are equal to if not surpassing a comperable MH system. Observed over a 9 month period with the exact same corals in my MH frag system.

- Color of corals is better. This is a very subjective statement, my Mona Lisa may be someone elses simple doodle.

- Color spectrum and adjustability is unequal.

- Temperature is moot, no chiller needed.

- Still have the same glitter lines and "lighting effect" of a MH system.

When you factor in that you will mostlikely not need to purchase a chiller to run a Solaris system or something similar, the price really does not seem that bad. Also factor in the energy usage of the chiller when comparing overall costs.

Again, I have not read all of this thread so if some of this was already covered I am sorry. And I am by no means a Physics / Lighting / Electrical Engineer expert type person. I just know what I see in the form of results.

If you feel that you need to shred what I said ..... please be gentle.

my $0.02

tyler

[PFO Lighting]

Lumileds has finally announced the LEDs we are using in the Solaris I4 series. These LEDs were officially announced today, but all the I4 series we have been shipping for the past 3 weeks have the white K2 with TFFC already installed in them.

LUXEON K2 with TFFC
http://www.lumileds.com/

Here is there press release.
http://www.lumileds.com/newsandevent...C_CW071115.pdf

I thought some of you technical people might be interested.

Thank You,
Patrick Ormiston
PFO Lighting Inc.

[BeanAnimal]

Thanks for the update patrick.

[killagoby]

This is my reef under an H series Solaris.



The lights are dimmed here to 70% on the day whites and 80% on the day blues. I don't think I will ever go back to halides. I'm very satisfied with Solaris. I wish the light was not so bright in this photo so you can see the colors of the corals in the middle and top of the tank.

[sherm71tank]

Looks like a nice collection of recently acquired corals and a relatively new tank to me.

[dhnguyen]

Originally posted by MorandiWine
To be honest with you, I have not read the entire thread so if I make a statement that was covered please excuse me.

We have a Solaris H4 series working at my business and I have sold a fair number of units to customers. Everyone that has bought a unit from my store has had nothing but good things to say. Keep in mind that half of these people we setting up their first reef and the remainder had had reefs in the past and were upgrading the lighting to the LED from MH, T5 and PC systems.

My personal observations are the following:

- Growth rates are equal to if not surpassing a comperable MH system. Observed over a 9 month period with the exact same corals in my MH frag system.

- Color of corals is better. This is a very subjective statement, my Mona Lisa may be someone elses simple doodle.

- Color spectrum and adjustability is unequal.

- Temperature is moot, no chiller needed.

- Still have the same glitter lines and "lighting effect" of a MH system.

When you factor in that you will mostlikely not need to purchase a chiller to run a Solaris system or something similar, the price really does not seem that bad. Also factor in the energy usage of the chiller when comparing overall costs.

Again, I have not read all of this thread so if some of this was already covered I am sorry. And I am by no means a Physics / Lighting / Electrical Engineer expert type person. I just know what I see in the form of results.

If you feel that you need to shred what I said ..... please be gentle.

my $0.02

tyler

Tyler,


Any pics of your SPS tanks running the Solaris?
What I don't see are SPS tanks using LED lighting. So far I've seen mostly LPS and softies tanks with a few small SPS frags or colonies.

Where are those SPS tanks under LED? Enquirer Minds want to know

[SWSaltwater]

Originally posted by dhnguyen
Tyler,


Any pics of your SPS tanks running the Solaris?
What I don't see are SPS tanks using LED lighting. So far I've seen mostly LPS and softies tanks with a few small SPS frags or colonies.

Where are those SPS tanks under LED? Enquirer Minds want to know

There are none, they can't run SPS. out of the thousands sold not one has SPS under it...........................

[JCTewks]

enough of the sarcasm SWsaltwater....just show us some pics of corals that were grown under LED's. It's pretty obvious that you are out to push the LED fixtures....so show us some pics of tanks lit by fixtures you have sold or currently own. dhnguyen's got a point....the only SPS i've seen on this thread that are under LED's are Frags in mostly LPS/Spftie tanks, and there is no obvious new growth in any of the pics of SPS i've seen.

So Show us the PICTURES

[MorandiWine]

Ok Ok Ok I'll take the camera to work tomorrow and take some photos.

Not to bring up a sore point, but it seems that the people that bash the LEDS the most are the ones that have not tried using them or have not seen them in action. Just an observation.

tyler

[JCTewks]

Personally I'm not bashing, I just would like to see some pics of actual growth...Everyone says they are great, but i've only seen tanks that look newly setup with frags in them or pics of a tank that has had the LED's on it for a whole week with all these stories about how wonderful they look and the corals are doing great!!! (but it's really only been a week )

and No, I don't use them...if I had $2000 to blow on the tank...I'm sure that my wife would have other plans for it

For something that costs that much...I'd expect it do start doing some chores around the house

[dhnguyen]

Nor am I bashing damnit

But what better way to prove thyself by showing us mortals some nice light intensive SPS corals basking under the LED sun

[Mutagen]

jcltok,

Let me start by saying I am certain that one day I will use LED light over my tanks. I love the concept and have been eagerly awaiting the LED application to aquaria. I may one day buy one of your products and will be happy to support your business. For me the initial investment is still a bit too high. But I do take some issues with some of your statements, especially in reference to how I appear to have been misquoted. I will get to that shortly.

Let me also say that I think a fair bit of the controversy in this thread has been related to the fact that it really is difficult to be explicitly clear on these forums. Clear and precise writing is not that easy to do. In particular, I think a number of references to "efficiency" have been used where sufficient clarity was not provided regarding what efficiency is being addressed. Bean made this point as well. Efficiency can refer to many things and make many different comparisons, and if they are not specified, mis-interpretation can be the result. I think some people are saying efficiency when they really mean efficacy.

For example: "I have (insert light type) over my tank and its looks great", is an aesthetic judgement and by itself has no bearing on efficiency and only somewhat on efficacy.

While "I have them on my tank it the coral growth and health have been better than ever", is a comment on efficacy but still not efficiency.

While " I have them on my tank and only consume 70% of the power", doesn't do the trick since it doesn't tell me how much light is actually reaching the tank relative to the power input. After all one can accomplish the same thing with by installing any lower power bulb.

While " I have them on my tank and only consume 70% of the power plus my tank looks better than before", is a step in the right direction.

But far better is " This system consumes 100 watts of electric energy and provides a total of 28 watts radiant energy in the visible spectrum. 60 watts of energy is dissipated as heat in the heat sink, 8 watts are lost with the cooling fans, and the remaing 4 watts are consumed by the control circuitry. The spectral distribution is (insert graph here)." Of the 28 watts of radiant energy 95% is reaching the surface of the water. The visible radiant energy hitting the surface equates to an average PAR of (fill in number). This would tell me I have a very impressive 28% efficient electric to visible light power converter, with almost all of the energy making to the water. A very impressive over all fixture. In this case, there is no ambiguity related to comments like "tank looks great", the color is better than ever", etc. And there is no debate about how much light is required since this debate also obscures the original simple question which was the energy conversion efficiency. For those who have made qualitative efficacy comments, don't get me wrong, they are important observations that others need and would like to hear, they just don't directly relate to energy efficiency.

I think many of the light tests people conduct are intended to at least attempt to get at something like the above quatitative assessment. Its simply not that easy to do, espcially not for a hobbyist with limited resources.

jcltok, now on to your comments.

1. LED provides a more precise light source than any other. The reason is that the LED is design to provide a vary narrow wavelength of light.

2. All current LEDs have a dip in the 475nm spectrum. Simply LED manufacturers have not found a precise phosphor for that spectrum range.

OK! good info, but not really answering any questions I posed, and specifically not referencing any efficiency questions.

3. You seem to confuse PAR with light output. They related but not the same. Light output is based on lumen and can be measured by a lux meter and then converted to lumen. You can also use a lumen meter to measure if the instrument has that function.

Light energy is very complex and I don't claim to understand all the math and physics required to model its behavior, but in this case I think you are the one who is more confused. Light output is not "based on lumen". The lumen is simply a unit of measure of light just like an inch or a meter is a unit of measure of length. (Visible) light is radiant energy typically defined as having a wavelength between 400 and 700 nm. The Lumen is not a good measure of light output for energy evaluation purposes. It is specifically weighted to the sensitivity of human eyesight as I said previously. I'll include a quote from Wikipedia now. If you examine the Wiki site you find much more about light measurement than you probably want to read! I find that reference useful since its really easy to confuse the various units with respect to which ones include unit area and unit time effects.

The lumen (symbol: lm) is the SI unit of luminous flux, a measure of the perceived power of light. Luminous flux differs from radiant flux, the measure of the total power of light emitted, in that luminous flux is adjusted to reflect the varying sensitivity of the human eye to different wavelengths of light.

Radiant flux is the value I needed to be able to compare apples to apples so that I could estimate the energy output as visible light divided by the energy input as electric power. It is impossible to get an accurate assessment of radiant flux from data expressed in Lumens without knowing the spectral distribution. So if you followed the logic of the analysis, that is why I had to "estimate" a wavelength.

Radiant flux expresses a power output as indicated by the Wiki quote. It is generally expressed as joules/sec wich is simply a watt. The watt is simply another unit that is not confined to describing only electric power.

PAR is a photon flux or perhaps more precisely a photon flux density. It describes a count of photons impacting a given area in a given time. Since each photon carries a specific amount of energy with it, PAR can also be considered an energy flux and be converted to units of energy per time per area. Therefore PAR (corrected for wavelength) is simply the radiant energy applied to a certain area per time unit. Conversely, PAR times area is radiant flux. In the case of lighting an aquarium, and a perfect reflector and no light losses and restrike etc, PAR (corrected for wavelength) times area will give the total output of the bulb in the visible spectrum. This is the calculation I was making to compare the two sources. This is why it seems that the MH bulb tested had an output some 4 to 5 times less than comparable MH bulbs, the reflector was useless, or something else interfered with the measurements.

PAR, measured with a quantum meter, should measure the output of evenly distributed 400nm to 700 nm wavelengths.

Why should the measurement of a photon flux depend on the spectral distribution being "even"? Should they be even in photon count or even based on the energy distribution since they are inherently differnent. Plus, the visible light incident on the earth or in the water is not "evenly" distributed at all.

Many MH manufacturers add exceptional amounts of violet/blue phosphors at the expense (lack) of other wavelengths, to manipulate the quantum/PAR meter into reading higher PAR.

I agree that the photosynthetic action curves do suggest that blue light has some advantages, but its my understanding that quantum meters actually measure the photon count and not the incident energy. Since the photosynthetic reaction mechanism has a one to one relationship with the number of incident photons and not the total incident energy, measuring a photon count would make sense (biologists feel free to correct if I am mistaken). High frequency (more blue) light will read lower on a PAR meter than red light when the total incident energy is exactly the same, specifically because of the way a quantum meter works, since it takes more red photons to get the same amount of energy. So building a bulb with more blue light will actually make the bulb appear less efficient than a bulb with a more "even" spectral distribution. Besides, weren't hobbyists switching to blue bulbs quite some time before the PAR meter data were generally available? (Caveat here, if in fact the quantum meter reads total energy and not photon count, then you are correct and I stand corrected)

Many MH manufacturers add exceptional amounts of violet/blue phosphors at the expense (lack) of other wavelengths, to manipulate the quantum/PAR meter into reading higher PAR.

and

Higher Kelvin does not mean better PAR. Higher KELVIN means bluer light.

I might be mising your points here, but aren't the two statements above contradictory?

Lumen and PAR should be measured at the water level, and not at the source.

Lumen and PAR can be measured where ever you want to measure them, just remember PAR is a per unit area measurement and Lumen is not. When talking about artifical light sources, it makes sense to talk about lumens/watt but not PAR/watt, unless more is known about the area being measured and any other parameters that will influence where the radiant energy is impinging. In nature, we don't care about the part of the sun's energy that is going out into space so referring PAR at sea level is still perfectly logical. It also makes sense to base one's measurements against a consistent standard, and water level is not a bad place to start. Again, the Lumen is a human eye weighted measurement of light energy per unit time.

8. You state you are frustrated by efficiency claims. You are correct in that when you have not been provided full information, every thing else is suspect. Some LEDs are very efficient at taking one watt and making more light - therefore the efficiency claim.

This was indeed the original question and I think somewhere in the thread it was almost answered. That is Lumen/watt was stated at some point. The next step is to convert Lumen into energy and we will be there. The DOE doc that Bean Animal pasted showed efficiency to be about 15%. But the technology is indeed changing quickly and it is almost certainly higher now. The simple question was by how much. Mostly we only see comments like "Some LEDs are very efficient at taking one watt and making more light - therefore the efficiency claim". But this is quite unsatisfactory to the consumer who wants to be able to separate hype from fact and see quantitative data. At least as I read the thread, that was the simple question. I am certain that all LED manufacturers and developers know this number, as it is critical in development, but for some reason prefer not to state them explicitly. As a manufacturer yourself, perhaps you can tell us why.

Also, as an aside, I did go to the Seoul Semiconductor web site and find a reference to the Lumen/watt output. I don't remember what it was but it was indeed respectable! However, the web site indicated the peak efficiency was when the LED was driven with 350 mA and not the 1000 mA where the LED's were run when the test in the review article was condcuted. How much does the efficiency drop when driving the LED's at higher output? There was no curve describing that relationship that I could find on the Seoul Semiconductor site. Maybe you could post that curve for us?

9. I have not seen your analysis of efficiency/output of LED vs MH. But, the proportions are likely close - you are basically correct in your conclusion. MHs are very inefficient as are fluorescents.

All I can say is WOW!. How did you interpret what I said to mean that ALL MH are inefficient.? Please allow me to clarify. I said the bulb and reflector combination used for the test was (apparently) very inefficient. I made no comment on any other MH bulbs and/or reflectors. I certainly didn't conclude anything at all about flourescent bulbs. I also said that the calculated result was in direct contradiction to rather well established efficiencies for MH type bulbs. Can you tell me what I wrote that led you to this conclusion? It is fine if you mean to say that is your opinion but it is a complete misquote of me. I did not intend to convey that meaning at all.

So let me rephrase. In the review article for the AI lighting system I believe the test data provided for the MH set up probably don't represent a fair comparison. This is because the apparent efficiency of the MH bulb was OUTLANDISHLY low. (This belief, I think is in agreement with some previous poster's statements.) On the other hand, using the same analytical technique, the output and efficiency calculated for the LED appeared to be in line with previously established LED efficiency data. The fact that the same analytical technique was used on the LED data and yielded a reasonable result provides some indication that the technique was valid. The large discrepancy between the expected and previously published results for the MH provides some indication there was "something amiss" with the data from the MH test. Not having been a part of the test work, I have no way to make any conclusions what so ever about the cause of the "something being amiss". While I can think of several possible causes, some of which might be easy to miss, it would be rediculously presumptuous for me to go down that road.

I was just trying to get at an explanation via a different path that had at least some amount of science behind it.

If anyone made it through all of this, wow, thanks for reading,

Tracy

[jnarowe]

I didn't. When I was setting up my reef, I researched LED lighting as best I could, and the quotes to deliver an equivalent PAR as MH was astronomical. I have seen several Solaris in action and I really like the control of output, but even when looking at comparative meters side-by-side, my eyes tell me there is less light eminating from the LED fixture. I also think tank depth is extremely important when considering LED lighting. With my 36" deep tank, my research just didn't bear out that LED could be used successfully, regardless of the cash outlay.

I also don't really buy into the less heat issue. LED fixtures get wicked hot, as do T-5 arrays and halides. It all depends on how you dissipate the heat. I use 1000W SE lamps on my tank, andhave no chiller. The fact is, if you don't keep LEDs cool, they will pop like popcorn.

[cclough_KeyDev]

Hi Tracy,

If you look at the charts contained in:

http://www.seoulsemicon.co.kr/_homep...pec/X42180.pdf

Specifically on pages 14 and 17, you'll see Relative Light output vs Temperature and Current respectively.

You'll see that it's not completely linear, but very close. 350mA is defined as 1.0, going up to ~2.4 @ 1A. This is where the 240lm @ 1A comes from. (You'll see this stated from us, as well as various press releases from Seoul Semiconductor)

This is the case with the white, but the blue follows the same trend.

If you maintain the temperature range that maintains ~100% output and drive at that current level, the efficiency stays the same.

It's all about temperature.

Hopefully this helps with the interest in the efficiency.

Best regards,
-Chris
AquaIllumination

Originally posted by Mutagen
Also, as an aside, I did go to the Seoul Semiconductor web site and find a reference to the Lumen/watt output. I don't remember what it was but it was indeed respectable! However, the web site indicated the peak efficiency was when the LED was driven with 350 mA and not the 1000 mA where the LED's were run when the test in the review article was condcuted. How much does the efficiency drop when driving the LED's at higher output? There was no curve describing that relationship that I could find on the Seoul Semiconductor site. Maybe you could post that curve for us? [/B]

[BeanAnimal]

Originally posted by MorandiWine
Ok Ok Ok I'll take the camera to work tomorrow and take some photos.

Not to bring up a sore point, but it seems that the people that bash the LEDS the most are the ones that have not tried using them or have not seen them in action. Just an observation.

tyler

1) More often than not, those that brandish the word "bashing", are not capable of (or willing to) debating the facts. The participants here are FAR from bashing anybody or anything.

2) One does not have to own or use a product to understand how it works. Some people have a much higher mechanical and scientific apptitude than others. I do not own neon signs but can tell you how they work. LEDs are not magic or mystical.

[jnarowe]

Come on BA, all that light from that tiny point? That's magical for sure! Imagine whipping one of those out in the 1600's...you get burned for being a witch!

[roblack]

Yes, people do have SPS tanks with the Solaris LEDs, I posted pics a while back. Look at my gallery and you will see them. THe light is bright and it is difficult to capture the actual color with my limited camera skills, but I have been working on it. SPS growing better under LEDs than MHs. Go figure...

[killagoby]

Originally posted by sherm71tank
Looks like a nice collection of recently acquired corals and a relatively new tank to me.

All of the corals are over 3 years old. The tank is 2 months new...

My LPS's are growing better under Solaris as well. Plus the light is much better than my 150w MH bulb. I can control it more and it is brighter. The MH bulb never burned out my corals like the Solaris did once I put it on at 100%.

[GSMguy]

Originally posted by killagoby
All of the corals are over 3 years old. The tank is 2 months new...

My LPS's are growing better under Solaris as well. Plus the light is much better than my 150w MH bulb. I can control it more and it is brighter. The MH bulb never burned out my corals like the Solaris did once I put it on at 100%.

nobody is debating the fact that they will grow low light corals.... this is not the argument....

I could Argue however that those results could have been gained by T5 for 15%-20% of the cost....

[jcltok]

Tracy,

I apologize for the following. You state “All I can say is WOW!. How did you interpret what I said to mean that ALL MH are inefficient.? Please allow me to clarify. I said the bulb and reflector combination used for the test was (apparently) very inefficient. I made no comment on any other MH bulbs and/or reflectors. I certainly didn't conclude anything at all about flourescent bulbs. I also said that the calculated result was in direct contradiction to rather well established efficiencies for MH type bulbs. Can you tell me what I wrote that led you to this conclusion? It is fine if you mean to say that is your opinion but it is a complete misquote of me. I did not intend to convey that meaning at all.” Tracy... My statement is an editorial one based on my research and you did not say anything to imply all MH are inefficient. Once gain my apologies!

Let’s talk about one thing at a time to avoid loosing track. To your central question about electrical efficiency, let me offer one example.

The REBEL 0080 LED puts out 145 lumen at 700 mA. Assuming multiple LEDS are running at 700mA, that means an output of 207 lumen per amp of electricity (by the way REBELS should only be run at 700 mA or their service life is significantly shortened). When I tested the light output of the REBEL LED it was 190 lumen at water level (the LED can be 1.5 inches above the water since it only transfers about 1 degree of heat over a 24 hour period). The REBEL runs at 12 volts so, the electricity used to create 190 lumens is 12 volts X 1 amp = 12 watts. 190 lumen from 12 watts or 15.83 lumen per watt of electricity.

When I surveyed various aquarium shops, I found 175 watt bi-ended MH lamps putting out 20,000 lux at water level (I only had a LUX meter which is the metric equivalent to lumen once some simple math is done). These MHs were at different heights above the water level to avoid heat transfer. To convert LUX to lumen you multiply the 20,000 lux X .0929 to get 1858 lumen at water level. 1858 lumen divided by 175 watts = 10.62 lumen per watt.

The REBEL 0080 LED provides 15.83 lumen per watt versus 10.62 lumen per watt based on the variety of MHs I tested. Obviously, there are many other LEDs that are not very efficient at all, but this is the basis for my statement regarding LED efficiency.

Let me review the Lumen issue since the explanation above is not plausible unless lumen measures are acceptable to you.

Radiance measures how much energy is released from any light source – the bulb or LED. Illuminance is what results from the light - how much light is hitting the water – which is what I consider important and corals depend on for life. The measure of how much light is falling on the water is measured in foot-candles which are exactly the same as lumen. 1 foot-candle is the amount of light put out by a “standard” burning candle one foot away on 1 square foot.

LUX is the metric equivalent of lumen. 1 LUX is equal to one lumen incident per 1 square meter of illuminated area. That is why you use the .0929 to go from metric to US units. We can get into “incident”, “steridians” and “candlepower”, but that is far from the scope of this discussion.

When I link lumen with balanced spectrum I mean that the light hitting the square foot has to have the color range the sun provides in the 400nm to 700nm range. Any radiance below 400nm is UV-A and any radiance above 700nm is UV-B. UV-A starts going into shorter wavelength and into things leading to x-ray and gamma, etc – no need to worry those waves are way smaller than what we are talking about. UV-B is near infrared and infrared – Sunburn stuff. Some MHs need a transparent shield to avoid hurting the coral with UV-A.

I hope this helps! What next?

Regards,

[jcltok]

Tracy,

OOps I got the UVA, AVB reversed.

[killagoby]

I've got it. I'm happy with it. God bless!

[hahnmeister]

"Any radiance below 400nm is UV-A and any radiance above 700nm is UV-B"

Joe, this is how it seems to me. You are getting into this reef lighting market, and have taken in alot of information very fast, but when you try to make sense of it, sometimes there are things you just dont know, and so when it comes back out, it may be 75% correct... but its just not all there.

"UV-B is near infrared and infrared – Sunburn stuff"
Wow. Stop embarassing yourself.

UV-C, or short wave UV, is about 280nm

UV-B is 320-280nm

UV-A, or long-wave, is about 400-320nm. C is deadly, B is for the most part as well. A isnt deadly, but the amount of energy it contains can easily overload and photoinhibit a coral.

wavelengths above 700nm are not UV-A or UV-B, they are INFRA RED.

Please, dont think this is something personal, but between this thread, and the other, what irks me is the amount of 'misinformation' you include in your posts. Sure, you might be 75% correct, but the truth is in the details. You are soliciting yourself as a guru, but it just isnt so.

This is just not true either: "Radiance measures how much energy is released from any light source – the bulb or LED. Illuminance is what results from the light - how much light is hitting the water – which is what I consider important and corals depend on for life. The measure of how much light is falling on the water is measured in foot-candles which are exactly the same as lumen. 1 foot-candle is the amount of light put out by a “standard” burning candle one foot away on 1 square foot. "

Radiance is not a measure of how much energy is being released from a light source. Radiant energy is one type of energy released from a light source, along with conduction and convection. Both the PAR and lumen scales are reading the same range and type of energy (light is energy or radiation... a form of heat)... the lumen scale is 'filtered' if you will because we as humans, dont percieve light fairly. But we cant use this scale for corals because the energy they use isnt 'filtered' like the lumen scale. We cant see UV, but we can sure feel it... and so can corals. Thats why the lumen scale isnt used for this market, and PAR is. Part of the radiance, or EM spectrum, which we see, is in 400-700nm. This is measured with a PAR or quantum meter. The range used for PAR meters can be changed, but is often adjusted to be 400-700nm. There is an extended PAR range though, considered about 300-800nm, which includes UV-A, some UV-B, and IR. So the range for a Lux meter and a PAR meter is the same visible light spectrum... its just that PAR is a 'true' or 'raw' energy number.... a lumen result is really the same thing, but percentages are taken of blue, red, and green so arrive at the final number... hence, the 'weighted' scale. But I think you are quite confused as to what PAR and lumens really are.

"Illuminance is what results from the light - how much light is hitting the water"

So is PAR buddy.

The way you explain this isnt true. PAR and luminance are the same thing, its just that the photometric scale is a weighted scale (and the units of measure are different)...
http://en.wikipedia.org/wiki/Luminous_flux
Read up.

Otherwise its really measuring the same thing as far as what you are saying. The reason PAR is a more accurate measure is because its what really counts. For land-based plants, the spectrum doesnt really change with 'depth'... as in, the spectrum remains a constant. But for corals, the spectrum changes alot once you hit just 5m of depth... the luminance drops considerably, yet somehow, due to all the blue light, the corals still grow. Its because corals dont care about lumens... they care about PAR. Same goes for land plants as well... its just that since there isnt a spectrum shift, its good enough.

"To convert LUX to lumen you multiply the 20,000 lux X .0929 to get 1858 lumen at water level. 1858 lumen divided by 175 watts = 10.62 lumen per watt. "

That whole thing is just wrong, wrong, wrong!!! There is no way you can convert lux to PAR/PPFD... you are talking two different things! You need to stop posting bad info. Also, you can not use a meter like that to get a lumen or PAR per watt figure!! It just doesnt work like that. There are reflectors in involved with what you did, so the intensity will vary with position. Lumens per watt calculations need to be done without a reflector, and are done by calculating the total incidental light from every angle around a light source, not by taking any spot readings. It can be determined by a point reading sometimes, if you know what your total area is and how it varies over that area, but you need integral calc to determine this ratio then.

You need a physics course on optics and the EM spectrum. Seriously... your info is just not right. You arent helping anyone.

Im shocked that Bean hasn't jumped on you already.