Aquarium LED Lighting – A Major Advance Or Is Metal Halide Still The Light Of Choice?

I’ve already written about LED’s (Light Emitting Diodes) of low output (see ‘LED Lighting On The Marine Reef Aquarium‘. Those low output LED’s create excellent moonlight effects. This time the subject is still LED’s but ones of high output.

The aquarist has had the choice of two major forms[ of lighting for the reef aquarium, first, fluorescent tubes, and second metal halides. Many very beautiful captive reefs have been lit using one or the other, or a combination of both. Fluorescent tubes have been used to great effect on soft coral reefs where light doesn’t need to be so powerful. Hard coral reef aquarists, however, have usaquaed metal halide bulbs because of the more intense illumination they provide. Many aquarists have supplemented this lighting with actinic fluorescent tubes for two reasons – to supply the blue light which satisfies the light needs of symbiotic algae, and to provide a light step-down system (dawn and dusk) by using timers, for the benefit of fish.

The light to be considered here in comparison to high output LED’s is metal halide. As said, metal halide is usually the light of choice for hard coral reef enthusiasts because of the high light output, and it is sometimes used on soft coral reefs. In addition to this, there are now available bulbs of 10000K, 14000K, and 20000K etc. (K = Kelvin = colour temperature.) The higher the Kelvin rating the more blue light and the cooler the colour appears.

So what’s this ‘major advance’? Metal halide is the light of choice, isn’t it?. For power output and Kelvin selectivity there isn’t a rival. That last sentence has been correct for a good while. However, there is now a rival and it looks good.

The new entrant is high power LED lighting. What is meant by high power? As I understand it, there are four LED arrays available at the moment. Two of these are rated at ‘250’ watts and ‘400’ watts, probably the most popular wattages for reef aquariums. So what? Well, there are some definite advantages to LED’s that metal halide cannot match.

To start, the LED array is contained in a rectangular box that hangs above the aquarium in the same way a metal halide would, though it could be hung considerably closer to the water surface if required. There are 25 LED’s in the array for every 12″ (the length of arrays vary from 14″ to 72″), 12 white and 13 blue (therefore the lighting colour is arranged in a similar way that fluorescent tubes would be).

The Kelvin rating of the LED’s is stated to be 20000. So it is just as suitable for corals. That is point one, LED’s equal metal halides in colour output.. So it is one all.

Metal halide bulbs need to be changed at two years (or less), to avoid light intensity reduction and spectrum shift. The LED lights can run for up to 50000 hours. Generally the ‘lights on’ period for a reef aquarium is 12 hours. This means the LED’s can run for 11 years! It is reported that there is a reduction of light intensity of 30% after that period. However, 70% light output after 11 years! If the metal halide bulb was changed every two years, five bulbs would need to be purchased – plus any supporting fluorescent tubes would need to be changed every year, so they would be changed 11 times. Two to one for LED’s.

A big problem with metal halides is the heat output. The radiated heat can and does warm up aquarium seawater. It can perhaps be reasonably argued that in cooler areas the heat from the metal halide bulb(s) cuts down on heater use. True – but what about summer, or reef aquariums in warm areas. The water heats up beyond the design temperature. If this temperature increase is regular enough and/or great enough then a chiller (cooler) is often employed. The LED unit, however, has been shown to direct heat away from the aquarium seawater. This is done by means of internal fans. The seawater is not heated up. I feel this lack of heat impact is important to the needed stability of the reef aquarium. So three to one for LED’s.

Metal halide bulbs emit UV radiation and need a UV shield to protect the corals (the corals may bleach with excessive UV). Hardly any UV radiation comes from LED’s. Four to one for LED’s.

The glitter lines produced by a metal halide bulb are very attractive and assist in making the captive reef appear more natural. LED’s also produce glitter lines. So that’s one each, five to two for LED’s.

The LED array has controls that will allow the light output to be adjusted for full sunlight, cloudy days, daylight, sunset or moonlight.. The LED bulbs can be dimmed from maximum output to zero output. Score, six to two.

Metal halides as said are able to light a beautiful reef. However, there is a cost. Electricity. Running one, two, three, or even more 150, 250, or 400 watt bulbs is expensive. The aquarist sees this when the postal service drops the bill! Included in this bill is the cost of running a chiller to control excessive heat rise in the seawater, applicable particularly in warm areas. In warm areas air conditioning may be in use, and the heat production of metal halide bulbs will not help the cost of running the conditioning. Any cost saving will be very welcome. The LED system may not be more efficient in energy usage than metal halides as far as light production is concerned. However, it has already been mentioned that heat is not transferred to the seawater, meaning a chiller unit will not be required (unless the areas normal temperature has a detrimental effect on the seawater anyway). The purchase cost saving on a chiller is worthwhile. The electrical running cost of a chiller is also saved. Assuming that the chiller would have been in use year on year, it is significant. If air conditioning is in use, then the conditioning has to deal with the heat put into the air by the fans on the LED system. The heat production of the LED system is stated to be ½ of metal halide, therefore the air conditioning will have less work. Score, seven to two.

The cost of a decent metal halide system is reasonable, not beyond the means of most aquarists. However, (yes, here it comes) the cost of an equivalent LED system is expensive. A ‘middle’ size LED system currently can cost circa $1800. Not cheap. However, the score might reasonably be considered as one all, as long term cost (potential electricity usage reduction, and bulb changing as opposed to no bulb changing) needs to be taken into account. So, eight to three.

To my knowledge, this is the biggest step forward in reef aquarium lighting systems for a long while, and a very exciting one. The aquarist with one of these LED units not only has a very adequate reef lighting system with a number of advantages over metal halide, but one that can be adjusted to simulate the light conditions that a wild reef encounters. In addition, in these times of environmental concern and ‘carbon footprints’, the aquarist would not only be successfully growing corals but might well be reducing the cost to the environment by using less electricity at the same time.

For any aquarist who would like to delve a little deeper, then please go to the following link:


  1. You have a major factual error in this article. The current generation of LED aquarium lighting is *significantly less* efficient than MH lighting — they use LEDs that generate fewer lumens per watt that a MH bulb would, therefore take more electricity to generate the same quantity of light. Less efficient.

    This will certainly change as LED technology evolves, but for the moment the core promise of LEDs (that of increased energy efficiency) isn’t fulfilled.

  2. Hi Andy. Thanks for that, I’m glad our efforts are being scrutinised. I admit to being somewhat non-committal in this area and thus wrote “If that is the amount of energy saved….” However, I do not dispute the point. I note that the manufacturer of the particular lighting system states “….air conditioner needs to work only 1/2 as much since the light fixture produces only 1/2 the heat of metal halides which saves even more energy”. I also note that the system “eliminates the use of a chiller.” The test report on the linked website supported the lack of seawater heating by the lighting system, so the chiller – and airconditioner – comments seem correct. The report also mentioned that an aquarist with the lighting system had been able to cease using a chiller. So, this is where the energy saving is coming from, it would appear. Important, particularly in warm areas. I’ll re-word the paragraph. Well spotted.

  3. Hi again.
    I felt sure I had seen ‘evidence’ of the quoted LED energy saving levels, so I did a bit of digging again.
    The statement comes under the 24″ LED Array:
    “The current design produces PAR light output levels equal to a 250W MH 20K. It uses 40% less energy than the metal halide fixtures it replaces…….”
    A pretty definitive statement it seems.

  4. Yes, but subsequently disproved by specification and testing.

    The particular LEDs (Luxeon III) used in the Solaris provide about 20 lumens per watt, MH bulbs provide around 50 lumens per watt. These are manufacturers’ specifications, not fudged data. MH bulbs *are* significantly more efficient than the Solaris. For an equal amount of light, the Solaris produces *more* heat than a MH bulb. To put it another way, for an equal amount of electricity the Solaris produces significantly less light than MH.

    Subsequent independent testing has supported these numbers.

    LED technology is advancing, though. Currently, there are LEDs on the market that produce 100 lumens per watt (twice as efficient as MH). Within the next few months, we should see LEDs that produce 150 lumens per watt. Aquarium lighting that uses these components will be far more efficient than MH lamps.

    There are lots of reasons to like the Solaris, but efficiency isn’t one of them.

  5. Thanks for the clarification. I assumed the Solaris manufacturer had got to the ‘improved’ LED stage hence the quoted efficiency. You quote the LED as “Luxeon 111”, and, going by the advanced aquarist report, the LED is the “Philips Lighting 3 Watt Luxeon Emitter”. So fair enough. I must say, I’m a little surprised that the manufacturer quotes incorrectly in the US market of all places!
    Thanks for your input.

  6. Even with the low lumens per watt, I still like the idea simply based on the energy saving in air conditioning and the cost of a chiller often necessitated by Metal Halides.
    This said I see much improvement ahead, including in price.
    Another lesser known innovation is the SHO light which is self ballasted and uses about the same space as the MH. The SHO produces about 60 lumens per watt and are currently available in 6400 K which is ideal for freshwater plant tanks. My understanding is that actinic are on there way.

  7. Hi Carl
    We appear to be in a period when the hobby is moving forward, at least as far as lighting is concerned. Can’t be bad, halides are terrific for a reef but the heat output and the energy consumption are unfortunate.

  8. Yes, I agree. I have seen very rapid changes in lighting technology over the last 15 years, including improvements in existing technology. What I find interesting is there is somewhat of a herd mentality going on in the aquarium trade. This has always been a problem here such as race of the herd to Wet/dry filters, bio wheels or other fads that have dominated this hobby.
    In lighting there seems to be a rush to T5 bulbs and even LED (although I see MEUCH promise here, just needs bugs worked out, including cost). Mean while technologies such as SHO which the mainstream lighting industry have embraced, as gone mostly unnoticed in the hobby (but for a few in the maintenance profession).

  9. Hi Carl,
    Thanks for the previous link by the way. I’ve clicked and found it very informative.
    It must be pressures of commercialism – marine aquarium outlets don’t want to stock equipment that is not particularly known or used. They want items that are known to be in demand, thought of as ‘market proven’. They are there initially for profit, it is their livelihood, and I have sympathy with this.
    Us aquarists are bad in ways as well. We buy equipment because of reputation and general knowledge of it in the hobby. Don’t want to waste money and want to support our livestock properly. My sympathy there too.
    It is a catch 22 really. This can be broken if one or two well known aquarists – Julian Sprung maybe, Bob Goemans maybe, etc, endorse the product. Confidence rises, sales begin.

  10. That was the best article on aquarium lighting I have ever read. It’s sort of a sales pitch and yet…honest. I’m sold and I’m going start planning my budgeting purchase for one of these.

    Thanks again.

  11. Thanks for the kind comments in relation to the article – we try our best to provide good content.

    Sorry that you thought it was a sales pitch as it certainly was not intended to be that way.

    If you do decide to get one then we would be very interested to hear about your thoughts and experiences with it.

  12. John,

    You mentioned that “As I understand it, there are four LED arrays available at the moment.”, I’m only aware of the Solaris range of lights, what are the other three?

    Thanks in advance!


  13. Andy,

    You were talking earlier about the Luxeon’s having 20 lumens/watt and MH around 50 lumens/watt. What you neglected to take account of is the balast required for MH. Far less than 50% of the energy into the plug goes into your bulb…and of course in regards to energy efficiency what goes into the plug is what matters.

    What’s more, allmost all energy wasted in the MH power supply goes up as heat into your room, all heat produced by the MH bulb is radiated directly into the tank. LED loses far less in the powersupply and the radiated heat is negligible.

    I’m not suggesting that the LEDs are more efficient overall than MH at this point, but at worst it is close and without doubt it produces less heat in the tank. What’s more, none of us doubts the efficiency will increase rapidly whereas MH is a mature technology.

    All The Best,


  14. You should check out this article where noted aquarium lighting expert Dana Riddle tests an LED lighting system against an the MH. The tests clearly show that the LED system is much more efficient.

  15. Hi Frank. Thanks for the link. I have actually seen it, and put an acknowledgement in the original text.

    If the price of LED’s would only come down….. 🙁

  16. iam so confused iam setting up a 225 gal show tank and iam stumped on lighting.But living in new york the savings sounds great on ac,chiller and elect.

  17. Hi.
    Confusion afflicts many newcomers to this hobby, and it is a shame as the hobby is basically straightforward.
    You may have already done so, but there are quite a few explanations in the Articles area: http://www.aquaristsonline/articles
    There is also a Forum in the social area where any question relating to marines can be put and hopefully answered:
    I believe that LED’s are the future of reef aquarium lighting. Fish only systems could continue to use fluorescents which are cheap enough to buy and to run.
    Metal halides have two major disadvantages, heat output and running costs. Both of these problems are avoided by LED arrays.
    If you are setting up a fish only system go for fluorescents.
    If you are to have a reef then metal halides are the lights currently in favour (often with fluorescent actinics as well). Also for the reef, and If you can afford them, check out LED’s.

  18. There seems to be alot of talk about led lighting.Iam in the mist of considering led lighting but the talk is saying the lumens are not strong enough but solaris is claiming its fixture puts out 80 lumens per watt irs seems to me this would be plenty.Does anyone run ther sytem with this fixture if so how well is it working for your stock.So confused in my area New York the energy savings means a great deal now that cost of electricity went up and is expecting another raise next year.

  19. Hello Frank.

    In my opinion LED lighting is the lighting of the future if not now – it emits the correct spectrum and the ability to contol the lights beats all else. Unlike halides it steers heat away from the seawater and the lights can even be dimmed to simulate clouds passing, or to give a ‘dawn and dusk’ effect. In addition LED lights last for years withour replacement, unlike fluorescents and metal halides.

    I find them exciting but am not an ‘expert’ on lighting sustems. I suspect that finding aquarists who actually use the LED system at the moment will be fairly difficult, their downside is their cost. Of course this is recovered in time with low running costs, no bulb replacements etc.

    I use a bank of actinic blue and marine white fluorescent tubes on my reef (soft corals). If I were rich I’d obtain an LED array (unfortunately I’m not). If I was planning an SPS reef and was in the design stage I’d balance out a suitably powered metal halide system against the cost of an LED array, taking into account running costs(electricity and bulb changes) and what additional advantages the LED’s or halides would give.

    If you are really stuck it could come down to what kind of reef you want and the depth of your aquarium. Fluorescent T5 lighting gives the necessary colour output for corals but has seawater penetration limitations. It is much cheaper to run than metal halides though.

  20. … I’m sure this is a layman’s question – BUT Still …

    How does one know if the LED’s reach the bottom of an aquarium enough?

    At the moment I am looking into LED version of MH lights for a 90 and 210 gal. reef tank set up – not really sure I actually need them all my corals look like they are thriving REALLY well ….

    even the Ricordia is growing (which I was told wouldn’t happen in my tank and I kind of figured they were wrong)

  21. Good one that Puddlekeeper. (Hey, I really like that name!)

    I haven’t any personal experience of main array LED lighting, I have only read a very small number of other aquarists experiences to date and read the reports on

    As said the numbers using LED arrays at the moment are very low because of cost of purchase. Comments following the article suggest that LED’s are advancing at a speedy rate.

    Can someone advise on LED penetration? Failing that, have a look at the ‘Contents’ part of the advanced aquarist report, should be a little enlightenment there.

  22. There seem to be several brandss on the market.

    I am sure the less expensive ones are so for a reason …

    What should my focus be on when I am trying to get something for my tanks?
    There are a bunch of $2.00 words which would cause me to spend weeks just to understand one of them … Can it be broken down in a way one might find in a book entitled “Aquarium LED Lights for Dummys”

    I am looking at justifying the expensive route compared to the frugal direction.

    There are light bars that connect together which could cost (on the excessive side) $400.00 compared to some which are 3 times that for one set up.

    Unfortunately; I am a least a little shy of a Marine Biology lab budget 🙂

    for under a grand I can light up my 90 and 210
    if I go the inexpensive way.

    There is an overwhelming amount of info for someone who two months ago had no extensive knowledge of REEF requirments.

  23. Hi again.

    I will try and be of some help – but before I commence I must once again point out that I am not a lighting expert, just giving as I see it using other experts knowledge as I interpret it, and that interpretation is no doubt pretty simplistic!

    If we base our consideration on the ‘advanced aquarists’ tests: they are comparing the Solaris 75 watt 20000K (=Kelvin which is colour temperature) LED Array with a 250 watt 20000K metal halide bulb.

    The spectrum output, that which is useful to and useable by corals (or rather the single-celled algae called zooxanthellae in the flesh of the corals), is suitable in both.

    The power output – intensity – is, as the tester advised, more difficult. What was done was the intensity was measured over an equal area at the same depth under each light type. It was found that the light output of the LED array was nearly 90% that of the metal halide, or in other words slightly over 10% less.

    So the light output is less, let’s call it 10%, with the LED’s.

    Perhaps we can make use of that figure.

    The guideline (note it is just a general guideline, not a rule) for keeping hard and soft corals in an aquarium using a 250 watt 20000K metal halide are as follows (that is, the light penetration factor that should generally be sufficient for each type of coral group):

    Soft corals: 68cm (circa 26 and 3/4″)

    Hard corals: 38cm (circa 15″)

    Quite a difference, reflecting the general lighting needs of each group.

    So, remembering the 10% less for LED’s, take 10% off the depth penetrations given and this could approximate to the penetration loss. It will not be accurate, and there are factors such as water clarity etc that affect penetration, but, as said, an approximation.

    Note that LED lighting is advancing, so it could well be that the current generation of LED’s is better. The test was carried out a time ago.

    Also note that the test was carried out on one manufacturer’s LED lighting array (Solaris), any other makes could be different.

    But… gives a foundation I hope, and may be useful.

  24. MH will become history in about 6 months. We are switching to 5mm LED throughout the store. Saving about $2500 a month on SMUD bill. 20% of MHs power consumption with no heat, bulbs replacement every 5 years. Sounds too good to be ture…..its happening.
    With 8 tubes of 12000k LEDs tube will outperform a 250w DE Hqi @30″ deep tank. The reading is about 250 with the Quantum meter. I just coun’t find anything negative about LEDs.

  25. Yes, the writing has been on the wall for metal halides for a while now.

    I don’t know about commercial systems, but the remaining problem with hobby units is the price. I hope these will fall substantially in time.

    Johns last blog post..Sponges

  26. I have noticed several people looking for an LED aquarium lighting system. We have a new system on the market at a price much less than the Solaris. This system has LED as well as two t5 ballast and reflectors. The reason we use the t5 in conjunction with the LED’s is for ambient lighting. The directional light from the LED does not reflect back out of the tank to your eyes. With the T5’s you dont have a shadowing problems the solaris had. Please stop by our website and take a look.

  27. Dont forget that metal halides are also sensitive to what is called a hot start and will burn out if the light is turned on then off and then back on. i don’t know how many times Ive turned off my tank light just to have some one ask to see the fish. also there is no reason for the prices to be that high. Ive done a lot of work with led lighting and I could easily build a fixture for much less. people are paying for the ability to say look at my cutting edge fish tank light.

  28. Please check this aquarium LED website, new LED product will be released every month!
    .-= hugh´s last blog ..High Power OceanBright Aqurium LED Lighting LED-L – $94.94 =-.

  29. its now 2010 and LED is the way to go for sure! people are still trying to sell that old solaris crap and diy but just do yourself a favor and look for a ho led setup (hopefully with some timers for the built in moon lighting and soft start, sundown phase) , i got one 8 months ago and my sps look as good as ever in my 29 gallon. im about to convert my 150 gal as soon as my tax return gets here.

  30. it is truly amazing how effeciant, effective and versatile LED Lights are.

  31. Hello.

    Yes and I reckon Led’s are the lighting system of the future. Prices remain a bit steep though running costs offset this to a point.

  32. Well there are alot of positives but if we actually look at this from an educated and scientific standpoint you must understand that t’5s and metal halide peak at 420/460nm ranges but have other ranges and have what we call a “Full Spectrum” where LED’s only hit exactly 6500K and 460nm Range. So they ONLY peak there so there isnt a full spectrum Thus detured Growth. So this is misleading because yes I have seen tanks maintained with LED’s but as far as SPS growth MH owns that world.So yes are they “Bright” and look great and cool yes. But would I advocate these … NO due to an Incomplete Spectal Output Thus No great Growth.. Don’t take my word for it… Research it. -Matt-

  33. Hi Matt.

    Yes, the argument continues. I am quite happy to accept that LED’s are still developing but they have advanced a long way. Cost seems to remain one of the downsides but open market competition should be having an effect by now. Depth of aquarium is another consideration. MH is still the major reef aquarium lighting used but for how long I wonder, with the downsides that are inherrent in the system, such as running cost, heat and relatively short bulb life.

    There are lots of articles and opinions on the internet which are easily found. I’ve listed some articles which could be of interest particularly the first. Specific equipment is mentioned but it doesn’t really matter.

  34. Depth of aquarium is another consideration. MH is still the major reef aquarium lighting used but for how long I wonder, with the downsides that are inherrent in the system, such as running cost, heat. this is very good to be here. wish you best of luck.

  35. Yes, I reckon that generally for reefs Led’s are the future of lighting if the cost reduces.

  36. Yes, I reckon that generally for reefs Led’s

  37. excellent post, thanks for sharing, digg it

  38. Glad you liked the post. It was written in September 2007 so, although the principles remain correct, LED’s could well have advanced considerably. Also there may be more LED lighting units available to aquarists at a lower cost.

  39. Yes I will continue to focus on

  40. Very interesting indeed , astonishing how it continues since 2007 to 2011
    I have MH 10,000 K 150W bulbs ( reeflux –> a very good PAR). .
    Here in Europ T5 are growing ( especially in Germany) , because od energy sparing …but T5 is not so cheap as far as energy is concerned .
    In France , we pay 0.07€ ( 0.1$) each kWh ( because of nuclear energy !) including taxes : 0.09€ /kWh = 0.128$/kWh
    So using a 250W MH bulb costs us 9,6$/month (10 hours a day)

    In Germany they pay twice our prices …( because few nuclear energy )
    So in France we are mainly used to use MH ( RX7S) , (added with 2xT5 ctinic ) but many reefkeeper prefer MH bulbs 20,000 K from 250W to 400W , although it cost a lot in energy consuming .
    Now interest for LEDs is growing on , but the fixture needs to be rich !
    It is seen as the reeflighting of the future , but still too expensive to buy .
    About heat : we can also admit that heating a 100 Gallons is expensive . Using a MH reduces heating the tank . It’s better to heat while lighting than heating out of lighting …
    It’s also possible to mind about how to recapture heat that is escaping from our tank …
    Another new lighting is Solatube … which is free !!( after being installed)

  41. Thanks for that – very interesting about electricity costs ‘nuclear and non-nuclear’. Prices are creeping uo (in the near future maybe jumping) and it will be important to check running costs as well as adequacy of lighting. I think the majority of reef aquarists who need high intensity lighting continue to use metal halides. The balance of choice could well swing towards Led’s if their initial costs reduce and I understand they are likely to do so. Things continue to develop. With regard to heating, on my reef I have a bank of five fluorescents (T8’s would you believe) and when they are on it’s clear that heating costs reduce – there is a ‘blinking’ exterrnal heating controller and the ‘blink’ reduces or goes off completely. The only thing then is to ensure the heat doesn’t rise too much!

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