Are LEDs a suitable primary light source?

However, determining if LEDs alone are viable sources of light, requires a better assessment. It’s certainly true that using multiple fixtures...
  1. jeremy.gosnell

    jeremy.gosnell Active Member R2R Supporter Article Contributor

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    Are LEDs a suitable primary light source?

    All images are public domain images courtesy of i stock and morgue file.

    Since the release of Ecotech’s Radion lighting, LED fixtures have become common over reef aquariums. In fact, the hobby saw an explosion of LED lighting, with nearly every brand of reef lighting releasing their own LED lighting system. LED lighting fueled the rise of a few new lighting companies which specialize only in affordable, reef capable fixtures. It happened fast and looking back, it seems as though LED lighting went from super expensive, too affordable, seemingly overnight. Many reef keepers saw only benefits when investing in LED lighting; the fixtures ran much cooler than traditional T5’s or metal halides, they used far less electricity and offered a full range of spectrums, re-creating an entire morning to night light cycle. Only now are we starting to see some of the downfalls of LED lighting. In many ways, the steady increase in reef keeper’s numbers may be tied directly to the rise of LED lighting.

    Shadowing appears to be a major concern, leaving some areas of coral totally un-illuminated. LED lighting is famous for creating hot-spots within the tank, areas where PAR (photosynthetic active radiation) is very high but available light falls off to unacceptable levels, just inches away.

    Reef keepers have learned that adopting LED lighting means either using a lot of fixtures or being very creative with coral placement. Some aquarists have abandon LED use altogether, reverting back to T5 fluorescent lighting or metal halides. Recently I added a 250-watt halide to my aquarium, which was a tough decision, since I once saw only benefits to using LEDs. While LED lighting is exceptional for creating a 24-hour day-night cycle, are they the best lighting option for growing coral? Will creative enhancements like Ecotech’s hemispherical edge illumination raise the bar for LED lighting? Or are the tried and proven lighting systems of yesteryear really the best option for growing coral?

    What are LEDs:

    LED infamously stands for light emitting diode. Simply put, they are a two-lead semi-conductor light source. When voltage is applied, an LED releases energy in the form of photons, thus creating light. This effect is known as electroluminescence and it separates LEDs from traditional light sources that use gas or chemical reactions to create light. Since LEDs are small, often an optical component (or lens) is used to shape their light pattern. This means that an LED light fixture is only as good as its lens.

    We often think of LED lighting as relatively new technology, yet the ability to create electroluminescence was discovered in 1907. It wasn’t until 1951 that the first LED lights were created, primarily for commercial and industrial purposes. LED lighting is a true single point light source, meaning that each individual diode creates a cone of light. Areas not illuminated by electrical discharge are filled with a vacuum of wasted heat. It’s this fact that makes them less than ideal for lighting a reef aquarium, an application that requires a light source that blankets everything. Even when a dense cluster of diodes is created, there are still areas entirely shaded, as the light beam created is cone shaped and leaves wide swaths uncovered by useable light.

    When placed over a reef aquarium, LEDs often fail to evenly distribute light. Areas of the tank right under an LED cluster often have a very high PAR (sometimes exceeding 700) yet isolated areas of the tank are left without a capable amount of light radiation. The result is shading, or shadowing, which leaves some corals without a blanket of light and can affect growth patterns. In some cases, corals are so light starved that they fail to thrive. The aquarist is mystified as to why under seemingly high output lighting their corals aren’t growing, or worse, slowly receding. It seems as though the cone of light produced by individual diodes cannot be increased by adding more LEDs to the cluster. A group of diodes simply creates one large, high radiation cone, with PAR levels that fall off just outside the cluster’s center.

    Are LEDs a viable primary light source:
    While T5 and metal halide lighting generate a lot of heat and use a lot of electricity, they both create a uniform blanket of light. T5 lighting is famous for creating an even spread of PAR readings from one end of a tank to another. While metal halide lighting does produce some shading, when combined with T5 fluorescent tubes, the entire tank is bathed in capable light radiation. We are now seeing aquarists combining LED lighting with T5 and metal halide, and the development of dimmable halide bulbs has increased their usage among reef keepers. Using a dimmable halide, it’s possible to create a day-night cycle not unlike that produced by LEDs, without the concern of spotty PAR readings. LED fixtures still maintain a premium price and often a tank needs quite a few to accomplish a robust lighting profile.

    While LED fixtures are sleek and easy to install under any application, they also make keeping light hungry corals challenging. It could be argued that when keeping SPS coral species, metal halide/T5 combination fixtures will still provide the best results. I personally added a 250-watt metal halide to my LED fixtures, largely because corners of the tank were getting under-served by active radiation. Over the past few halide-less years, I had forgotten the allure of the rich light they produce and as soon as I booted the fixture up, I was taken back to the warm glow of halide only lighting. It’s certainly arguable that no other lighting solution provides such a rich, fluid blanket of light.

    However, determining if LEDs alone are viable sources of light, requires a better assessment. It’s certainly true that using multiple fixtures creates acceptable PAR readings throughout even a large reef aquarium. However, it’s tough to get totally accurate PAR readings from every nook and cranny within the tank. One issue with LED lighting comes from the nature of using diodes to produce useable light. Diodes create a cone of light, with the center of the cone being the area of best output. While LED light spreads out, it becomes less useable by photosynthetic organisms the farther away from the diode’s center a coral gets. Given that many popular LED lights contain two, three or four pucks of multiple diodes, there is relatively isolated spots of powerful, useable light. Depending on how a coral is placed, areas of the surface may be shadowed and even though it appears the specimen is illuminated, in reality it’s getting little useable light.

    In my reef, PAR readings within 10 inches of an LED puck’s output range, a few inches below the water’s surface, usually hover around 250-300, dropping sharply the deeper an object is. Outside of that 10-inch range, PAR quickly drops to 160 on down to 100 and below. Considering that even LPS corals often grow best under blue spectrum light of at least 200 PAR, this can make for challenging growing conditions. Adding an additional fixture creates another lighting hotspot, which similar range. Many aquarists install LED lights thinking they are capable of growing corals in a 24x24 inch area of a tank. This is solely dependent on how the corals are placed and the depth of the tank, along with how high the lights are mounted. This fact has also encouraged the development of “frag flat” style tanks, which use a shallow build to maximize light penetration. We want coral frags to grow a uniform pattern with lots of surface area, making a desirable colony. Shadowing and PAR drops can cause corals to grow strange patterns, where one area of a coral has accelerated growth but other areas maintain dwarfed, due to lack of useable light. I would say that using LED lighting only requires careful, creative placement of corals, to ensure all the animals are getting adequate light.
    By adding a 250 watt, 14k metal halide in the center of two hanging LED fixtures, I was surprised by the changes in PAR. Dropping deeper into the tank, where PAR usually dropped below 200, the halide was able to maintain 260 PAR within 18-20 inches from the halides’ center. In higher areas of the tank, within 20 inches away from the halides’ center, PAR in excess of 300 was available. Also, coral frags such as montipora and acropora are bathed uniformly in light, eliminating dead spots where tissue bleaches or becomes discolored. I lost a quarter sized chunk of growth in the middle of a large montipora colony in the center of my tank, since it sat right in the medium zone between two high intensity LED outputs. There simply wasn’t a good why that I could bridge that gap with light. Now that a halide has been in place for several months, that gap is closing up with measurable growth week by week. It’s quite impressive.

    The LED dilemma:

    While LED light fixtures cost more than metal halides, they are also far sleeker and very energy efficient. They don’t require nearly as large an external ballast to run, and LED ballasts often run much cooler than a comparable metal halide ballast. The frustrating and bulky design of metal halides is absent when using LEDs and the slim style of LED fixtures make them easy to mount in a variety of ways. LEDs also offer the aquarist a host of different lighting spectrums and colors, making it very easy to showcase the colors of various corals. However, it seems as though regardless the number of fixtures, their output or distance between the water’s surface, issues with shading and dropping PAR are present.

    Some aquarists consider LEDs more of a secondary light source as opposed to a primary one. Much how T5 tubes are combined with metal halides, a combination of LEDs and halides gives aquarists powerful, uniform and blanketing light and complete control over photoperiod and color. While combining halides and LED does work, the aquarist loses many of the benefits brought forth by LED lighting. Once again, lighting is using a lot of power and generating a lot of heat. While most LED fixtures create less heat than T5/halide combos, they aren’t without the need to be cooled internally by a fan.

    For aquarists, it’s becoming a buzz-kill. Several years ago, when LEDs began to dominate reef tanks, it seemed as though we were getting our cake and eating it too. Though, the reef aquarium hobby moves slowly and with several years of LED only lighting under the collective reefing communities’ belt, shortcomings are being identified with these next generation lights. For moderate reef aquarists who are after a pretty tank with as little hassle as possible, LED lights often work quite well. But for those of us trying to maximize growth rates and achieve the best polyp extension and coloration (especially in SPS corals) sometimes LEDs alone fall short.

    In my personal view, it requires aquarists to make a choice, when determining the future of their system’s lighting profile. If you are satisfied with measurable coral growth and overall healthy colonies, along with a bit of restrictions on what species you can keep, but don’t want to hassle with mitigating heat and multiple light sources, chances are an LED fixture will work fine. However, if you’re dead set on the use of water quality, amino-acids, feeding and other methodologies that push coral growth to the limits, then it’s very likely you will want to invest the time and money into a multiple light source profile. The allure of metal halides is strong, as they create arguably the most beautiful and dynamic light of any reef capable light source and many aquarists are pleased to continue using them. However, in the long run, they are expensive and far from hassle free – but the same goes for reef keeping as a hobby as well.
     
    Last edited by a moderator: Oct 31, 2016
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  2. reefwiser

    reefwiser LMAS R2R Supporter Reef Squad R2R Excellence Award Article Contributor

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    Your links are wrong
     
  3. revhtree

    revhtree Owner Administrator Staff Member Team R2R R2R Supporter Photo of the Month Award R2R Excellence Award Partner Member 2019 Build Thread Contributor Article Contributor Cyber Monday Sponsor

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    It's because you're using Tapatalk and TT doesn't work with our site very well.
     
  4. Birddog

    Birddog Hooked on Reefing R2R Supporter Partner Member 2019

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    Great thought provoking article Jeremy, thank you!
     
  5. reefwiser

    reefwiser LMAS R2R Supporter Reef Squad R2R Excellence Award Article Contributor

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    After using LED's only for the last couple of years. I have found that I need to add some T5's to the mix to get the growth that I want.
    Shadowing is a concern with my SPS.
     
  6. jeremy.gosnell

    jeremy.gosnell Active Member R2R Supporter Article Contributor

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    LEDs can be a bit deceiving, especially because they don't follow the conventional "rules" of reef tank lighting. Years ago, in the days of power compacts and metal halides, we used to judge a light's suitability for a tank based on watts. There were suggestions like 3 watts per gallon for some species, 5 watts per gallon for others; and many aquarists sized their light fixtures based on those specifications. It was one reason that metal halides were so popular, because they had such a high wattage people often believed they could keep a wide array of coral species. Whether the wattage per gallon rule was ever true to form, I am not sure, but I am sure that halides and T5's were quite good at growing corals. LEDs are so different from either halides or T5's not only does the wattage per gallon rule not apply, traditional rules don't seem to either. I have had corals seemingly bathed in LED light start to wither. A PAR test shows a mediocre amount of useable radiation, even though the coral appears brightly lit. The rise of consumer/hobbyist level, easy to use PAR meters (I personally use Neptune's but several are now on the market) has helped aquarists start to notice the flaws in LED lighting. (They can't really be called flaws, as its more the nature of LEDs and how they create light energy. For most applications, shadowing isn't much of an issue) About a year ago, I got a PAR meter and started doing testing myself. I was surprised that PAR dropped so quickly outside of LED fixtures "hot" range. I thought it must have been my fixtures, which at the time was the Ecotech Radion Generation 3 pros. I got a new set of fixtures, Kessil's AP700s and found the same exact issues. So I started testing other sources of light: T5 and eventually metal halide. I was quite surprised by how much more coverage I got from mixing metal halide with LED. I imagine mixing T5 w/ LED would have similar results.

    I want to be clear that I am not degrading LEDs or suggesting they aren't capable of keeping a beautiful reef aquarium, we know that they are. I am just suggesting that now that the hobby has had a few years of heavy LED use under its belt, it's time we start looking at the nuts and bolts of how they work and the results they produce, since many aquarists are reporting similar experiences and there appears to be a sudden re-emergence of T5 and halide use among reef keepers. Trust me, it took a lot for me to even consider adding a metal halide to my tank, largely because I am such a fan of LEDs efficiency and sleek/simple nature, plus full daylight to moonlight profiles. In the end, I try to push my corals growth and coloration outside the realm of many reef keepers and I frag often and grow many frags into colonies. Based on that, I felt the best way to achieve that was to add a halide to the mix. The example I wrote about in the article (the montipora colony) was surprising to me, as I didn't expect the result to be so dramatic.
     
  7. chino402

    chino402 Member

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    The problem with LEDs is most people don't use enough of them for sps tanks. And run them too strong for LPS and Softy tanks. While T5s users have T5 tubes over every single corals, LED users Would throw 2 radions on a 150 gallon and want to go sps dominate lol That's clearly not enough.
     
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  8. Wiz

    Wiz Valuable Member Reef Tank 365 Build Thread Contributor

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    Although my mixed reef did awesome over the past year with led only, I added a t5 fixture to bring the color out more during the day and increase my growth rate. But the led actinic can not be out done and growth was less but still stable without them.
    So I think led is very sustainable alone but ideally a combo will get better results. But ohhhhhh the outlets I'm taking up with multiple fixtures lol.
    Great read. :)
     
  9. Justfbilly

    Justfbilly Active Member Build Thread Contributor

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    I have 2 65 gallon reef tanks. One tank I am running T5's and metal Hailides and the other tank in running LED's. Both tanks have SPS and LPS but the tank with the LED's everything grows like weeds. I have even gone as far are buying 2 of the same frags and putting one in each tank and with in weeks there is a noticeable difference in the LED tank.
     
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  10. Salty1962

    Salty1962 Wrasse and SPS Lover R2R Supporter Reef Squad R2R Excellence Award Build Thread Contributor

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    Nice write Jeremy, thx for sharing! Thought provoking information.
     
  11. jeremy.gosnell

    jeremy.gosnell Active Member R2R Supporter Article Contributor

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    I had felt for some time that the advertising around LED fixtures, such as the area of useable light (which is often advertised as 24x24) was stretched to the max. I don't think LED manufacturers are being outright dishonest, just that the natural way LEDs produce light, mounting options, current within the tank and other factors skew how an LED fixture performs on any given tank. My personal testing with a PAR meter confirmed my suspicions which were based on coral growth from various areas of my tank, in relation to their distance from an LED's hot light center. PAR drops off quickly when you move from the bright focal point of the LED puck, which makes sense as this is the area of greatest LED light discharge. Oddly enough, I have gotten complaints from home owners about light oddities when they switch to LED lighting in their homes. Something about the light spread seems off to them, and they have a hard time explaining it. I don't know for a fact that shading, shadowing and light spread from LED in comparison to traditional lighting is to blame, but I imagine it could be. It's important that reef keepers understand that originally, LED lights were developed for blinking road signs, digital advertising and outline lights for car headlights, etc. Expecting LEDs to replicate perhaps the highest intensity light radiation on the planet (the tropical sun over a shallow-water coral reef) is taking the technology to a whole new level. If you compare how a metal halide works (creating a lighting arc via gaseous mercury and metal halides) to how an LED works (creating light via recombining electrons to release energy in the form of photons) they really aren't comparable. Yes, LEDs use far less electricity and generate far less heat, but the chemical and electrical process that creates the light is very different, thus is the light that is actually produced.
     
  12. jeremy.gosnell

    jeremy.gosnell Active Member R2R Supporter Article Contributor

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    Another thing I noticed in researching for this article, that I should have included: is that simple environmental factors within the tank had a more profound effect on PAR reaching corals when using LEDs v. other lighting methods. Why this is, I don't know and my findings are entirely anecdotal (which is why I left them out of the main article). However, they are worth mentioning. Using LED fixtures alone, I found a drop of 6-10 PAR when my return and circulation pumps caused considerable agitation at the water's surface. Altering the circulation and return pump output returned most of that lost PAR back to the tank. I also found a drop of around 12 PAR when I placed my screen top over my tank, using LED lighting alone. My screen top is a large frame, clear plastic mesh similar to many of the screen tops in use by reef keepers. Since removing the screen top isn't an option (as I have several fish species prone to jumping) using LED alone I would have to live with that PAR loss.

    With metal halides, I found a PAR loss of about 4 when my return and circulation pumps we causing surface agitation and 7 with my screen lid. Why it's so different, I don't know. Like I said, overall minimal and anecdotal - but interesting none the less.
     
  13. drodge

    drodge Member

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    I'm relatively new to the hobby and have spent a lot of time here reading and trying to avoid some mistakes. I have a Red Sea Max 250 and have had it running for about 6 months or so. I've got quite a few frags and they have been growing very well and look great so far. The issue I've had is the tank temps have been very high and I usually leave the top open to allow it to cool during the day. I even considered adding a chiller to cool things off while the lights are on. Just this past weekend I retrofitted the hood with a Rapid LED setup and replaced the existing T5's. The temps have dropped dramatically and the tank looks amazing. After reading this article and others, I now wonder if I'm going to hurt the coral growth. One thing I haven't seen mentioned much is LED lenses. It makes sense that if the issue with LED's is the light emission pattern, then using a lens to disperse the light more evenly could help. Has anyone tried them or done a side-by-side comparison? Thanks.
     
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  14. jeremy.gosnell

    jeremy.gosnell Active Member R2R Supporter Article Contributor

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    Some could argue that an LED is only as good as its lenses, and it would be an argument with merit. Lenses make a huge difference in how LED light is disbursed. Ecotech (which my auto-correct swears is Scotch) hopes to revolutionize lens technology with their upcoming hemispherical lens. We will have to see how the new lenses perform once they are released. One thing worth noting, it takes a lot of time to really notice subtle changes in how a lighting type performs. For a while, even for several years, things can seem relatively in line with previous results, but as our tanks evolve and we closely monitor coral health, it's often then that shortcomings become apparent. My point, aquarium media and various aquarists may very well claim that Ecotech's new lenses (or any new product for that matter) has sealed the gap regarding LED lighting concerns, but in reality it will take a long time and the reports of a lot of reef keepers to really paint a complete picture.

    One thing worth noting, there are so many variations between individual LED diodes, lenses and configurations, it's impossible to pan LED lights as universally insufficient. In fact, if an aquarist invests time and effort into monitoring their PAR readings and carefully placing their corals while using only LEDs, chances are they will achieve good results.
     
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  15. JMacedo

    JMacedo Active Member

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    LEDs are perfectly suitable as a primary light source and can grow just any type of coral. 20160914_110131[1].jpg
     
  16. tvu

    tvu Active Member

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    JMacedo can you share your tank specs? Very nice tank.
     
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  17. JMacedo

    JMacedo Active Member

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  18. Reefcowboy

    Reefcowboy Well-Known Member

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    "growing sps is easy, bringing them to max color is an art".
    It has been done over and over with Leds, some just need to learn how to.
     
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  19. saltyfilmfolks

    saltyfilmfolks Lights! Camera! Reef! R2R Supporter Reef Squad Leader Photo of the Month Award R2R Excellence Award Build Thread Contributor

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    nope. you wont. just try not to over light. look into lux meters. but your probably fine.

    a lot of side by sides have been done and both work. Just differently/

    Look into "SHading" and "shadowing" here on r2r2 a lot of good conversations here.

    a good one
    https://www.reef2reef.com/threads/what-are-you-doing-to-reduce-shadowing.264195/page-2#post-3160146

    Its a bout how and where you place the led for coverage on the tank. one lens is not for all tanks at all heights and learning how to use and place them is the trick for most. A t5 you just put over the tank. an led array not so much. because of the lenses
     
  20. Reefcowboy

    Reefcowboy Well-Known Member

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    Insane coloration, can you discuss a bit about your tank, lighting? Good job, it is beautiful
     
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