Photon Wars: LED, T5, & Halides Illuminated
Photon Wars: LED, T5, & Halides Illuminated
Of all the questions I get asked about reefkeeping, the one I get asked by far the most is, "Which lighting is right for me?", a question that even today takes a lot of reasoning and rationalisation to give a coherent answer. It's never a definitive answer because the simple fact is everything will do the job adequately where generation of useable photons is concerned, but it's always one considered on a number of metrics that I'll go into in this article to help you make a similar judgement. The very crux of it is, though, that drawing factions will not work as all setups call for different criteria to be satisfied and so different technologies will be applicable - as an aquarist trying to make the best of things we need to be able to discern this objectively.
To cut to brass tacks - when put on a level playing field, all forms of light we employ will generate sufficient usable radiation - that is, when employed using similar spectra and relative intensity, at any given point the light in most cases will be capable of sustaining photosynthetic life of some kind. The razor of separation arises however when we come to catering to the specific needs of particular inhabitants. As there's a major deviation of required photosynthetically active radiation (PAR for short, measured in µmol photons/m2/second - an expression of photosynthetic photon flux density) required to achieve photosaturation in the broad range of photosynthetically-reliant inhabitants commonly found in aquaria, so too there's major deviation in what can actually achieve it. This concern should be, above all else, the criteria you select based upon - relative to your system, if you're attempting to keep things which are unsuitable for the choice you have in mind (either too strong or too weak), you'll invariably cause damage to the inhabitants in one form or another. This can be tricky to assess... but it's not impossible.
Metric #1: Livestock Requirements
To explain the prior point better, take a common situation: a mixed reef in a 4x2x2' aquarium. For this, you wouldn't use a pair of 400W 6500K metal halides because there is simply no need for such high levels of photon generation and so it is automatically precluded from selection (quite aside from everything, it'll cause serious harm to the inhabitants). Equally, you wouldn't want to go for a single of the lowest powered lights you can find (say, 50W LED panels) because in all likelihood it won't cater to the livestock in the system (you can fudge it, vaguely, by increased feeding - but there's a point this becomes impractical/impossible).
It does raise an interesting point however - what's called Goldilocks Syndrome. As a result of our insistence as reefers to keep things which are, for all intents, incompatible in their requirements, we run into a situation where things will sustain life but a lot of the time not quite meet the optimum (and is a huge reason I harp on about the benefits of a biotoped system... but that's for another time!). In this particular case, however, you'd have options which are roughly analogous in terms of their ability to generate PAR/PUR - maybe 6 reasonable quality 54W T5HOs (324W + ballast inefficiency) (or 4x 54W for high-end - totalling 216W + ballast inefficiency), 2x 120W LED units (240W + AC/DC conversion loss), or 2x 150W Metal Halides (300W + ballast inefficiency). Which is best in this case? Well, that's where more metrics come into play.
Metric #2: Financial Requirements
The next metric is, as a necessity, what can you actually sustainably afford on a macroscopic scale - both in initial outlay and incurred/ongoing outlay? Nobody really likes budgeting, let's face it. It's tedious at best, and really a huge downer on what should be an enjoyable sideline. But, needs must... and so, we draw it up with pros and cons for all and use it as an objective assessment that will form part of the bigger picture.
In the long term, it's quite apparent that the LEDs will draw quite a bit less power (realistic estimate would be approaching 100W) at any given time than the other two alternatives in most situations barring the actively cooled T5HO, and has an added benefit of not having much radiated heat which is projected downwards into a system. The buy-in, for a reasonable quality unit... that's where LED really falls flat on its face. Because the components this is built around are exceptionally expensive per Watt (roughly $5.50/W at current to buy as a consumer the parts alone), the entire technology is expensive. You can recoup some of it from not needing to run a chiller as often as other forms of light, but on balance it does have a long way to claw back.
The T5HO option here is middle of the road in terms of real-world power usage by virtue of tending to have more efficient ballasts to Metal Halides, however in terms of upkeep it can be quite expensive if you're not familiar with places to get gear for a reasonable cost. On most fixtures which are not actively cooled, when employing quality brands, a good lifetime for tubes should be seen as approximately 9 months. This means you'll be purchasing 2 new sets of tubes (12 in this example) in the first 18 months of ownership. A positive is, on a radiant heat basis they tend to produce less per Watt than Metal Halides as well, meaning some of the outlay is recouped in minimised chiller costs. For proper high-end fixtures which employ several technologies to improve efficiency (active cooling to help maintain surface temperature of the tubes at T5-specifcation 35ºC, quality individual parabolic reflectors, high efficiency ballasts), because of their increase in PAR per Watt we can effectively reduce the power and tube requirements for the given application - effectively reducing ongoing costs at the expensive of initial outlay.
The most power-hungry will generally always be the Metal Halide option of a given set, based on the relative inefficiency of it in transferring current to radiant flux (by comparison to T5HO and LED anyway). Anyone who's ever stood around Metal Halides knows that their biggest strength is also their greatest weakness - even though they produce a hell of a lot of light in their illumination pattern, with it comes a hell of a lot of heat too. It can be really rather unpleasant to be around during the warmer months... but on the upside, it's a good way to save on your heating bills during Winter...? Seriously though, Halides will require a fair amount of output and usage from your chiller to keep things under wraps. They also will require replacement of lamps at least annually, with the best brands being quite expensive (>$150 as of this writing). That having been said, they are far and away the cheapest to buy into per Watt, leaving the others long behind. It's cheap and available, and if the hype is to be believed, proven. Probably worth mentioning at this point, another downside with Metal Halide that doesn't often get figured in is that many high-PAR lamps are deficient in the blue end of the spectrum (460nm and below) relative to other wavelengths in their mix and so typically require T5HO/T12VHO/LED additional to offset and create an appealing visual effect (the other reason is also because going from no lights to full lights can really shock the hell out of your inhabitants...).
Metric #3: Aesthetic Requirements
That last point leads us neatly onto the subject of aesthetics. That is to say, how the light actually looks in the tank and makes the inhabitants respond. Let's face it, for all we harp on about meeting the demands of our inhabitants, we really will come back to ourselves very heavily at the end of the day. Simple fact is, if the tank looks horrible, we're not gonna look at it and derive enjoyment from it in the same way we would if the light was perhaps slightly less ideal but looked better to our eyes. For this reason, aesthetics is an incredibly important metric to use when we buy lights. This is personal - some people can't live without "shimmer" (properly caustics) in their tanks, some people love colours that "pop", some people love a "crispness" to their light - in effect there is very little to this that isn't subjective (which means you'll need to be familiar with how the light looks yourself unless someone is really good with adjectives). In some regards we can quantify this metric using objective generalisation. For example, it's fair to say that if you simply must have shimmer in your tank, T5HO is not the light for you as it will produce relatively minimal owing to being non- point-source. If you need the ability to tweak your overall colour with ease, many LEDs will suffer in this regard. If you want the crispest light possible, LED will tend to prevail.
The best way to summarise this point is, go and see it with your own eyes in the flesh. It's easy to say lighting has x, y, and z properties, but until you actually physically see it render in a real-world application the theory behind it is relatively meaningless.
Metric #4: Availability
It’s sort of a wasted gesture to want something you can’t actually have, yes? This metric takes care of that. Personally there are about 30 different types of light I’d simply love to own, but of course, when you live on an island in the middle of the sea isolated from everything actually getting them is a whole other kettle of fish. This really applies to everything we get, and actually, it integrates with the others pretty directly. It seems to be unless you know somebody who has contacts or can get stuff directly from Europe or Asia; you’re left out in the cold. Our market isn’t big enough to really warrant direct manufacture for us for many products. This needs to be carried in mind when narrowing your selections.
Of course, this isn’t to say if you want it can’t be had, just that if it’s not directly available here you will go through hell to get it. Be prepared, fortune favours the brave.
Metric #5: Maintenance Requirements
As with anything else in the world of reefkeeping, our lights should undergo frequent and routine maintenance to keep them in their absolute peak performance to make sure their photon potential is at the best it can be for our inhabitants. Obviously this includes simple things like keeping reflectors and guard glasses clean of saltspray, adjusting heights as needed, so on, so forth… but beyond that there’s always a necessary measure of input needed dependent on what technology you actually employ.
Far and away, LED will require the least additional work to make sure they’re serviced. This is due to their purported lifespan – in most cases being beyond 50,000 hours of useful lifespan – which in effect means that by the time they’re suggested to wear out, a new technology will very likely exist to replace it anyway. As such, the likelihood in which you’ll need to physically change emitters is relatively low. Some fixtures have this functionality which allows for the adjustment and replacement of individual emitters, so while not a specific maintenance concern this does allow for colours to be changed for more suitable ones as technology advances.
T5s, oh dear. This is a big negative for them. Having to replace a multitude of tubes at least annually can be a tedious and trying time, especially when you don’t turn an endcap properly or you put the tubes in incorrectly. There are few things in life to inspire this much hate. It also is a lot more reflector space to clean down if you’re not using a cover glass, meaning you’ll need to take the tubes out to properly get all salt spray off… is it all sounding like a big chore yet? More tubes means a lot more work. Be mindful of this, because it’s more than many are willing to put in.
Halides aren’t so bad. Annual lamp replacements, occasional reflector clean-downs (which in the case of Single-End variants anyway won’t involve removal of the lamp), cover glass clean-downs in the case of Double-Ended/UV-shielded variants, and that’s just about it. Halides come through from it very well it must be said. Supplemental T5s here will still need the same care as in the last paragraph so don’t get too excited just yet, but Halide is in and of itself relatively maintenance-free.
Metering the Metrics: The Maths Part
I’ve been doing this over literally hundreds of instances so it is pretty easy for me to go through this list and compose something in a matter of seconds, but unless you’re familiar with the weighting you should be using it can be rather daunting. No problems, it’s quick to pick up and make easy decisions with a little maths.
To make this simple, we’ll structure it as a table. Then, we’ll score each option out of a possible 100, which obviously will yield us the most practical solution. To construct it, it’ll look like this:
METRIC
SCORE
Livestock Requirements
Weighted from 0 – 50.
Financial Requirements
Weighted from 0 – 20.
Aesthetic Requirements
Weighted from 0 – 20.
Availability
Weighted from 0 – 5.
Maintenance Requirements
Weighted from 0 – 5.
TOTAL
Total from 0 – 100
Now, this table is what we use for each option. Basically, the higher the score, the better an option will be for your application. This is where it gets a bit tricky… because it relies on you being totally honest about each option. While it’s easy to colour perception of things based on what we really want, this doesn’t meet the idea of this at all – it’s intended to give us an objective reflection of all options.
Basically, score like this. If you’re keeping our hypothetical 4x2x2’ mixed reef, 400W halides would score fairly low on the livestock requirements, perhaps around a 10. It’ll do the job, granted, but it’ll do it quite poorly (whereas say, a pair of 90W LEDs would get pretty close to top marks here). Financial requirements will come down to your budget – if they’re well in budget they get full marks, if they’re perhaps above your budget by a hundred dollars or so they’d get middling marks, and if they’re way out of range they get very low marks. The rest are easy – if it meets the criteria for what you want of a light in that particular metric, you mark high, if it doesn’t, mark it low.
We take this total, and weight it against other options. Annnnnd, providing your budget can allow for it and your stockist can provide it, you have found your new lighting. Hopefully. This does hinge on your own honesty with yourself though. If you’ve been dishonest, your livestock will be the first to show you up for it (and your wallet too, probably). So, don’t fool around yeah?
Hopefully that’s helped! Happy reefing, may the future be bright.
- Professor Moosejaw.
Of all the questions I get asked about reefkeeping, the one I get asked by far the most is, "Which lighting is right for me?", a question that even today takes a lot of reasoning and rationalisation to give a coherent answer. It's never a definitive answer because the simple fact is everything will do the job adequately where generation of useable photons is concerned, but it's always one considered on a number of metrics that I'll go into in this article to help you make a similar judgement. The very crux of it is, though, that drawing factions will not work as all setups call for different criteria to be satisfied and so different technologies will be applicable - as an aquarist trying to make the best of things we need to be able to discern this objectively.
To cut to brass tacks - when put on a level playing field, all forms of light we employ will generate sufficient usable radiation - that is, when employed using similar spectra and relative intensity, at any given point the light in most cases will be capable of sustaining photosynthetic life of some kind. The razor of separation arises however when we come to catering to the specific needs of particular inhabitants. As there's a major deviation of required photosynthetically active radiation (PAR for short, measured in µmol photons/m2/second - an expression of photosynthetic photon flux density) required to achieve photosaturation in the broad range of photosynthetically-reliant inhabitants commonly found in aquaria, so too there's major deviation in what can actually achieve it. This concern should be, above all else, the criteria you select based upon - relative to your system, if you're attempting to keep things which are unsuitable for the choice you have in mind (either too strong or too weak), you'll invariably cause damage to the inhabitants in one form or another. This can be tricky to assess... but it's not impossible.
Metric #1: Livestock Requirements
To explain the prior point better, take a common situation: a mixed reef in a 4x2x2' aquarium. For this, you wouldn't use a pair of 400W 6500K metal halides because there is simply no need for such high levels of photon generation and so it is automatically precluded from selection (quite aside from everything, it'll cause serious harm to the inhabitants). Equally, you wouldn't want to go for a single of the lowest powered lights you can find (say, 50W LED panels) because in all likelihood it won't cater to the livestock in the system (you can fudge it, vaguely, by increased feeding - but there's a point this becomes impractical/impossible).
It does raise an interesting point however - what's called Goldilocks Syndrome. As a result of our insistence as reefers to keep things which are, for all intents, incompatible in their requirements, we run into a situation where things will sustain life but a lot of the time not quite meet the optimum (and is a huge reason I harp on about the benefits of a biotoped system... but that's for another time!). In this particular case, however, you'd have options which are roughly analogous in terms of their ability to generate PAR/PUR - maybe 6 reasonable quality 54W T5HOs (324W + ballast inefficiency) (or 4x 54W for high-end - totalling 216W + ballast inefficiency), 2x 120W LED units (240W + AC/DC conversion loss), or 2x 150W Metal Halides (300W + ballast inefficiency). Which is best in this case? Well, that's where more metrics come into play.
Metric #2: Financial Requirements
The next metric is, as a necessity, what can you actually sustainably afford on a macroscopic scale - both in initial outlay and incurred/ongoing outlay? Nobody really likes budgeting, let's face it. It's tedious at best, and really a huge downer on what should be an enjoyable sideline. But, needs must... and so, we draw it up with pros and cons for all and use it as an objective assessment that will form part of the bigger picture.
In the long term, it's quite apparent that the LEDs will draw quite a bit less power (realistic estimate would be approaching 100W) at any given time than the other two alternatives in most situations barring the actively cooled T5HO, and has an added benefit of not having much radiated heat which is projected downwards into a system. The buy-in, for a reasonable quality unit... that's where LED really falls flat on its face. Because the components this is built around are exceptionally expensive per Watt (roughly $5.50/W at current to buy as a consumer the parts alone), the entire technology is expensive. You can recoup some of it from not needing to run a chiller as often as other forms of light, but on balance it does have a long way to claw back.
The T5HO option here is middle of the road in terms of real-world power usage by virtue of tending to have more efficient ballasts to Metal Halides, however in terms of upkeep it can be quite expensive if you're not familiar with places to get gear for a reasonable cost. On most fixtures which are not actively cooled, when employing quality brands, a good lifetime for tubes should be seen as approximately 9 months. This means you'll be purchasing 2 new sets of tubes (12 in this example) in the first 18 months of ownership. A positive is, on a radiant heat basis they tend to produce less per Watt than Metal Halides as well, meaning some of the outlay is recouped in minimised chiller costs. For proper high-end fixtures which employ several technologies to improve efficiency (active cooling to help maintain surface temperature of the tubes at T5-specifcation 35ºC, quality individual parabolic reflectors, high efficiency ballasts), because of their increase in PAR per Watt we can effectively reduce the power and tube requirements for the given application - effectively reducing ongoing costs at the expensive of initial outlay.
The most power-hungry will generally always be the Metal Halide option of a given set, based on the relative inefficiency of it in transferring current to radiant flux (by comparison to T5HO and LED anyway). Anyone who's ever stood around Metal Halides knows that their biggest strength is also their greatest weakness - even though they produce a hell of a lot of light in their illumination pattern, with it comes a hell of a lot of heat too. It can be really rather unpleasant to be around during the warmer months... but on the upside, it's a good way to save on your heating bills during Winter...? Seriously though, Halides will require a fair amount of output and usage from your chiller to keep things under wraps. They also will require replacement of lamps at least annually, with the best brands being quite expensive (>$150 as of this writing). That having been said, they are far and away the cheapest to buy into per Watt, leaving the others long behind. It's cheap and available, and if the hype is to be believed, proven. Probably worth mentioning at this point, another downside with Metal Halide that doesn't often get figured in is that many high-PAR lamps are deficient in the blue end of the spectrum (460nm and below) relative to other wavelengths in their mix and so typically require T5HO/T12VHO/LED additional to offset and create an appealing visual effect (the other reason is also because going from no lights to full lights can really shock the hell out of your inhabitants...).
Metric #3: Aesthetic Requirements
That last point leads us neatly onto the subject of aesthetics. That is to say, how the light actually looks in the tank and makes the inhabitants respond. Let's face it, for all we harp on about meeting the demands of our inhabitants, we really will come back to ourselves very heavily at the end of the day. Simple fact is, if the tank looks horrible, we're not gonna look at it and derive enjoyment from it in the same way we would if the light was perhaps slightly less ideal but looked better to our eyes. For this reason, aesthetics is an incredibly important metric to use when we buy lights. This is personal - some people can't live without "shimmer" (properly caustics) in their tanks, some people love colours that "pop", some people love a "crispness" to their light - in effect there is very little to this that isn't subjective (which means you'll need to be familiar with how the light looks yourself unless someone is really good with adjectives). In some regards we can quantify this metric using objective generalisation. For example, it's fair to say that if you simply must have shimmer in your tank, T5HO is not the light for you as it will produce relatively minimal owing to being non- point-source. If you need the ability to tweak your overall colour with ease, many LEDs will suffer in this regard. If you want the crispest light possible, LED will tend to prevail.
The best way to summarise this point is, go and see it with your own eyes in the flesh. It's easy to say lighting has x, y, and z properties, but until you actually physically see it render in a real-world application the theory behind it is relatively meaningless.
Metric #4: Availability
It’s sort of a wasted gesture to want something you can’t actually have, yes? This metric takes care of that. Personally there are about 30 different types of light I’d simply love to own, but of course, when you live on an island in the middle of the sea isolated from everything actually getting them is a whole other kettle of fish. This really applies to everything we get, and actually, it integrates with the others pretty directly. It seems to be unless you know somebody who has contacts or can get stuff directly from Europe or Asia; you’re left out in the cold. Our market isn’t big enough to really warrant direct manufacture for us for many products. This needs to be carried in mind when narrowing your selections.
Of course, this isn’t to say if you want it can’t be had, just that if it’s not directly available here you will go through hell to get it. Be prepared, fortune favours the brave.
Metric #5: Maintenance Requirements
As with anything else in the world of reefkeeping, our lights should undergo frequent and routine maintenance to keep them in their absolute peak performance to make sure their photon potential is at the best it can be for our inhabitants. Obviously this includes simple things like keeping reflectors and guard glasses clean of saltspray, adjusting heights as needed, so on, so forth… but beyond that there’s always a necessary measure of input needed dependent on what technology you actually employ.
Far and away, LED will require the least additional work to make sure they’re serviced. This is due to their purported lifespan – in most cases being beyond 50,000 hours of useful lifespan – which in effect means that by the time they’re suggested to wear out, a new technology will very likely exist to replace it anyway. As such, the likelihood in which you’ll need to physically change emitters is relatively low. Some fixtures have this functionality which allows for the adjustment and replacement of individual emitters, so while not a specific maintenance concern this does allow for colours to be changed for more suitable ones as technology advances.
T5s, oh dear. This is a big negative for them. Having to replace a multitude of tubes at least annually can be a tedious and trying time, especially when you don’t turn an endcap properly or you put the tubes in incorrectly. There are few things in life to inspire this much hate. It also is a lot more reflector space to clean down if you’re not using a cover glass, meaning you’ll need to take the tubes out to properly get all salt spray off… is it all sounding like a big chore yet? More tubes means a lot more work. Be mindful of this, because it’s more than many are willing to put in.
Halides aren’t so bad. Annual lamp replacements, occasional reflector clean-downs (which in the case of Single-End variants anyway won’t involve removal of the lamp), cover glass clean-downs in the case of Double-Ended/UV-shielded variants, and that’s just about it. Halides come through from it very well it must be said. Supplemental T5s here will still need the same care as in the last paragraph so don’t get too excited just yet, but Halide is in and of itself relatively maintenance-free.
Metering the Metrics: The Maths Part
I’ve been doing this over literally hundreds of instances so it is pretty easy for me to go through this list and compose something in a matter of seconds, but unless you’re familiar with the weighting you should be using it can be rather daunting. No problems, it’s quick to pick up and make easy decisions with a little maths.
To make this simple, we’ll structure it as a table. Then, we’ll score each option out of a possible 100, which obviously will yield us the most practical solution. To construct it, it’ll look like this:
METRIC
SCORE
Livestock Requirements
Weighted from 0 – 50.
Financial Requirements
Weighted from 0 – 20.
Aesthetic Requirements
Weighted from 0 – 20.
Availability
Weighted from 0 – 5.
Maintenance Requirements
Weighted from 0 – 5.
TOTAL
Total from 0 – 100
Now, this table is what we use for each option. Basically, the higher the score, the better an option will be for your application. This is where it gets a bit tricky… because it relies on you being totally honest about each option. While it’s easy to colour perception of things based on what we really want, this doesn’t meet the idea of this at all – it’s intended to give us an objective reflection of all options.
Basically, score like this. If you’re keeping our hypothetical 4x2x2’ mixed reef, 400W halides would score fairly low on the livestock requirements, perhaps around a 10. It’ll do the job, granted, but it’ll do it quite poorly (whereas say, a pair of 90W LEDs would get pretty close to top marks here). Financial requirements will come down to your budget – if they’re well in budget they get full marks, if they’re perhaps above your budget by a hundred dollars or so they’d get middling marks, and if they’re way out of range they get very low marks. The rest are easy – if it meets the criteria for what you want of a light in that particular metric, you mark high, if it doesn’t, mark it low.
We take this total, and weight it against other options. Annnnnd, providing your budget can allow for it and your stockist can provide it, you have found your new lighting. Hopefully. This does hinge on your own honesty with yourself though. If you’ve been dishonest, your livestock will be the first to show you up for it (and your wallet too, probably). So, don’t fool around yeah?
Hopefully that’s helped! Happy reefing, may the future be bright.
- Professor Moosejaw.
