**DISCLAIMER** Outside of the graphs this is not a entirely scientific analysis. The images are all copyright Sanjay Joshi and Advanced Aquarist. This is merely my interpretation/opinion based on Sanjay's talk at MACNA along with our conversation since MACNA. Let me state that I have lit 5 tanks with LEDs and have switched my current tanks to metal halides.
Obviously the hot topic in lighting right now is LEDs and there are more opinions out there then options for them. People are using LEDs of all color mixes, wattages, and brands to successfully grow corals. I think the question is how do you BEST sustain and grow corals using this more efficient, long term cheaper lighting solution.
First a couple of definitions so we are all on the same page:
Lumen-total light emitted by the light source, as percieved by the human eye
Lux-amount of illumination provided when one lumen is evenly distributed over an area of one square meter
PAR- is any light in a specific frequency range of 400 to 700 nanometers that is needed by plants & symbiotic zooanthellic algae
PUR-Photosynthetically Useable Radiation. It is also known as "useful light energy"
I am going to use the Spectrum Analysis of an Ushio 14k Metal Halide bulb as the basis for this post as that is the bulb of choice by Sanjay himself. Let add in that he is running halides only with no supplements on his 500g reef tank.
Here is the spectrum analysis of the Ushio 14k:
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Looking at this you can see a very jagged bell curve with spikes at: 360, 410, 420, 430, 450, 540, 575, 680, 700. These spikes prove key because these wavelengths are strictly in the RGB spectrum; meaning Red, Green and Blue. As you will notice there is no white. These colors mix together to give us white light. There are different temperatures of white light that we use the term Kelvin to describe. Below you will see a Correlated Color Temperature(CCT) graph. On this graph there are verticalish lines marked 2000, 3000, 5000, 8000, 10000 etc The horizontal line that crosses these will continue to either side of the graph therefore giving us the 12000, 14000, and 20000 that we are so accustomed to seeing. What you will notice is that the vertical lines extend beyond the horizontal line. Any bulb that emits light at any place on this vertical line is classified under that CCT. For example if you look at the 10000 line; at the top the color is almost teal yet at the bottom it is more pink but both are considered 10000K.
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The problem with LEDs is that each LED hits a much more narrow spectrum than a metal halide or T5 bulb. When you buy a blue LED (depending on manufacturer) you are getting the 460-490 spectrum, where as royal blue is 440-470 and cool blue is 470-500. Because of this many colors of LEDs are required to achieve the same results as a metal halide. Below is a list of some of the LEDs that I have found by different manufacturers and as you can see not all LEDs colors are created equally. Notice there is no white on here. A white LED is actually a blue LED with a phosphorus coating over it. The white LEDs in a fixture are there so that we can actually see into our tanks. Because of the narrow spectrum it would be very difficult to accomplish but we should be able to create the right mix of the colors below and blend them together perfectly to create white light(do not try this at home unless you have lots of time and money!!)
[attachment=0]led colors.jpg[/attachment]
Now for PAR. PUR is the useable portion of PAR and each different photosynthetic species will have a different PUR range to which they respond; which is why different corals respond better to different lighting. PAR and LEDs is a very hot topic and it has even been rumored that LEDs can not be measured with a PAR meter only a LUX meter: this is FALSE. PAR/PUR is what our corals need to survive not LUX. It is a common statement that (1) 3watt LED is as good or better than (3)1watt LEDs. I believe this to be false. 3 watt LEDs are actually less efficient than 1watt LEDs in their output and based on tests by Sanjay their PAR values in the are not as high take a look at the graphs below.
First is the Ecotech Radion XR30W(34-3watt LEDs) which has a max par of just under 200:
alt="">
Next is the Ecoray 112 LED (112-1watt LEDs) which has a max PAR of just under 600:
alt="">
Total wattage of the Radion is 102w, total wattage of the Ecoray is 112w. So the wattage is close enough for comparison. The Radion is a better full spectrum fixture using 5 different colors of LEDs where the Ecoray only uses 2 colors but the PAR values are not even close. This is one of those times where I think quantity is better than quality. If there was a way to swap out lets say 1/3 of the white LEDs on the Ecoray and replace them with UVs, greens, and reds then I would say you would have an excellent fixture.
Summary:
*Should everyone go throw out their 3w LED fixtures? NO just verify that they are covering the spectrum that your corals need to survive.
*Do I believe that LEDs are ready to replace MH in the hobby? NO but with some proper research you can achieve similar results.
*What is the right combination of LED colors for a full spectrum fixture? Based on the Ushio 14k spectrum analysis if I were to build one it would be:
-3 UV
-3 royal blue
-2 blue
-2 cool blue
-1 cyan/turqouise
-3 green
-1 pink
-1 red
-4 cool white
-4 neutral white
I would place the blue and (2)UV on 1 driver, whites on 1 driver, colors and (2) UV on 1 driver to be dimmed seperately. Obviously that is 24 LEDs so if you need more to cover your tank then just multiply each number by 2, 3, 4 etc depending on your total number desired.
*I personally would rather have a fixture with 100-1watt LEDs in the above configuration than 33 in the above configuration. Not only will you get better blending of your colors but based on the graphs shown your PAR/PUR numbers should be better.
Once again this is not entirely scientific, but is my opinion based on looking at the studies done by Sanjay on spectrum and LEDs combined with some logic. Here is a well thought out full spectrum fixture built by our own bimmerz viewtopic.php?f=1&t=92278.
Obviously the hot topic in lighting right now is LEDs and there are more opinions out there then options for them. People are using LEDs of all color mixes, wattages, and brands to successfully grow corals. I think the question is how do you BEST sustain and grow corals using this more efficient, long term cheaper lighting solution.
First a couple of definitions so we are all on the same page:
Lumen-total light emitted by the light source, as percieved by the human eye
Lux-amount of illumination provided when one lumen is evenly distributed over an area of one square meter
PAR- is any light in a specific frequency range of 400 to 700 nanometers that is needed by plants & symbiotic zooanthellic algae
PUR-Photosynthetically Useable Radiation. It is also known as "useful light energy"
I am going to use the Spectrum Analysis of an Ushio 14k Metal Halide bulb as the basis for this post as that is the bulb of choice by Sanjay himself. Let add in that he is running halides only with no supplements on his 500g reef tank.
Here is the spectrum analysis of the Ushio 14k:
Looking at this you can see a very jagged bell curve with spikes at: 360, 410, 420, 430, 450, 540, 575, 680, 700. These spikes prove key because these wavelengths are strictly in the RGB spectrum; meaning Red, Green and Blue. As you will notice there is no white. These colors mix together to give us white light. There are different temperatures of white light that we use the term Kelvin to describe. Below you will see a Correlated Color Temperature(CCT) graph. On this graph there are verticalish lines marked 2000, 3000, 5000, 8000, 10000 etc The horizontal line that crosses these will continue to either side of the graph therefore giving us the 12000, 14000, and 20000 that we are so accustomed to seeing. What you will notice is that the vertical lines extend beyond the horizontal line. Any bulb that emits light at any place on this vertical line is classified under that CCT. For example if you look at the 10000 line; at the top the color is almost teal yet at the bottom it is more pink but both are considered 10000K.
The problem with LEDs is that each LED hits a much more narrow spectrum than a metal halide or T5 bulb. When you buy a blue LED (depending on manufacturer) you are getting the 460-490 spectrum, where as royal blue is 440-470 and cool blue is 470-500. Because of this many colors of LEDs are required to achieve the same results as a metal halide. Below is a list of some of the LEDs that I have found by different manufacturers and as you can see not all LEDs colors are created equally. Notice there is no white on here. A white LED is actually a blue LED with a phosphorus coating over it. The white LEDs in a fixture are there so that we can actually see into our tanks. Because of the narrow spectrum it would be very difficult to accomplish but we should be able to create the right mix of the colors below and blend them together perfectly to create white light(do not try this at home unless you have lots of time and money!!)
[attachment=0]led colors.jpg[/attachment]
Now for PAR. PUR is the useable portion of PAR and each different photosynthetic species will have a different PUR range to which they respond; which is why different corals respond better to different lighting. PAR and LEDs is a very hot topic and it has even been rumored that LEDs can not be measured with a PAR meter only a LUX meter: this is FALSE. PAR/PUR is what our corals need to survive not LUX. It is a common statement that (1) 3watt LED is as good or better than (3)1watt LEDs. I believe this to be false. 3 watt LEDs are actually less efficient than 1watt LEDs in their output and based on tests by Sanjay their PAR values in the are not as high take a look at the graphs below.
First is the Ecotech Radion XR30W(34-3watt LEDs) which has a max par of just under 200:
Next is the Ecoray 112 LED (112-1watt LEDs) which has a max PAR of just under 600:
Total wattage of the Radion is 102w, total wattage of the Ecoray is 112w. So the wattage is close enough for comparison. The Radion is a better full spectrum fixture using 5 different colors of LEDs where the Ecoray only uses 2 colors but the PAR values are not even close. This is one of those times where I think quantity is better than quality. If there was a way to swap out lets say 1/3 of the white LEDs on the Ecoray and replace them with UVs, greens, and reds then I would say you would have an excellent fixture.
Summary:
*Should everyone go throw out their 3w LED fixtures? NO just verify that they are covering the spectrum that your corals need to survive.
*Do I believe that LEDs are ready to replace MH in the hobby? NO but with some proper research you can achieve similar results.
*What is the right combination of LED colors for a full spectrum fixture? Based on the Ushio 14k spectrum analysis if I were to build one it would be:
-3 UV
-3 royal blue
-2 blue
-2 cool blue
-1 cyan/turqouise
-3 green
-1 pink
-1 red
-4 cool white
-4 neutral white
I would place the blue and (2)UV on 1 driver, whites on 1 driver, colors and (2) UV on 1 driver to be dimmed seperately. Obviously that is 24 LEDs so if you need more to cover your tank then just multiply each number by 2, 3, 4 etc depending on your total number desired.
*I personally would rather have a fixture with 100-1watt LEDs in the above configuration than 33 in the above configuration. Not only will you get better blending of your colors but based on the graphs shown your PAR/PUR numbers should be better.
Once again this is not entirely scientific, but is my opinion based on looking at the studies done by Sanjay on spectrum and LEDs combined with some logic. Here is a well thought out full spectrum fixture built by our own bimmerz viewtopic.php?f=1&t=92278.
