jeasko
Fishaholic
Lighting your aquarium is a subject that is continually cropping up especially with the addition of new technology such as LEDs, the lack of understanding of lighting so often leads to poor decision making on what will work best in your aquarium, with that in mind and a little nudge I have put together some info for newbies and experienced aquarists in this hobby, please excuse the typo's in this though as I haven't yet had a chance to proof read it
This article will hopefully give you some information that will enable you to make an informed choice of what best to use In your own environment, I will state before I go any further that this will unlikely give you a definitive answer in what you should use to light your aquarium, simply for the reason that there are normally multiple options that will have similar results. And ultimately it's the hobbiest choice
For those that are new to the hobby I'll give a break down of each of the different types of lighting and some pro's and cons for each, I'll also try and cover a few other considerations that even some of the most experienced aquarists among us may not be aware of.
The old rule of thumb with lighting especially with reef setups was to use x watts per gallon, with light efficacy (efficienacy of light output) improving this rule has really dropped by the wayside, to put this into some context Flourescent light tubes give between 30-90 lumens per watt and MH (metal halide) gives between 65-120 lumens per watt with led surpassing MH lighting with lumens per watt.
So it's easy to see why watts per gallon is no longer really applied, as the results could be dramatically different if applied across the board, for example a 10w fluorescent tube may give out 300 lumens where as a (theoretically as 10w mh to my knowledge doesnt exist) 10w mh lamp could give 650 lumens!
What kelvin lamp?
For the most part people believe that the degree kelvin rating has very little relevance and is purely aesthetic, however this is not so, reefers tend to keep within around 10000K - 20000k with the 20000k being far more blue in colour than the 10000k which is more yellow
The K rating does though have a dramatic affect on your tank and in my opinion ( and this is my personal opinion) is almost equally as important as PAR (which will be discussed later) why? In short and to try and keep it simple blue light is the last colour to be absorbed by water meaning it penetrates deepest, so by putting a higher K rated lamp which has more blue in it you can be sure light penetrates to the darker depths, there are a few pit falls to be aware of though.
One of the biggest things reefers overlook is the depth of thier aquarium in relation to what K lamp works best, below is just a guide and is by no means a definitive be all and end all answer to what works for you as You may decide to use more than one different k rated lamp especially if your using a T5 luminaire.
Tanks 12-20 inches 10000k will strike a good balance of coral growth as well as tank aesthetics
Tanks 15-30 inches 14000k lamps will be a better option as light will penetrate deeper
Over 30 inches 20000k with supplementary lighting to light higher in the water column as this will have Little useable light Which may result in Coral growth slowing
As you can see from above there is an overlap on the 10000 & 14000k lamps so this is to a degree the users choice, these should all be used in conjunction with actinic lighting which is not just for aesthetical purposes as there are photosynthetic invertebrates (clams nudibranch etc) that need this light, as a word of caution 20000k lamps should be used wisely as over 15000k there is very little useable light for corals etc unless it is supplemented with additional light to light the shallower water, but I'm guessing there aren't that many people with 2.5ft deep tank?
PAR (Photosynthetically Active Radiation) and PUR
(Photosynthetically Useable Radiation)
PAR as stated in the title stands for Photosynthetically Active Radiation which is a specific band of light between approx 400-700 nanometers which plants, coral and symbiotic zooanthellic algae require to survive, however while it is important it's only able to be measured using specific meters and more importantly it's not PAR per say that is the crucial element that's required for coral and plants to grow as not all PAR is useable by plants and coral, the part that we should be concerned with is PUR (Photosythetically Useable Radiation) PUR is that fraction of PAR that is absorbed by zooxanthellae photopigments thereby stimulating photosynthesis which we see as coral and plant growth, Without delving too far into this subject which is likely to cause confusion and raise more questions than answers I'll summarise this subject
As PAR meters are not particullarly accurate and PAR is not necessarily useful (led luminaries can emit high PAR but low PUR) and PUR is virtually Impossible to measure (to my knowledge there is no meter available for this) we tend to go back to kelvins as we know from history and test that the light penetration is sufficient to provide ample PAR and PUR it's for this reason that I state Kevin is an important consideration in choosing which light to use
Different Lights
T12, T8, T5 &T2 lighting
Common place at the moment are T5 flourescent tubes, the T indicates tubular and the 12, 8, 5 & 2 all indicate eighths of an inch diameter so a T5 is a tubular 5/8 of an inch diameter flourescent light, coincidentally the longer the tube the higher the wattage.
These lights are usually sufficient to keep soft corals and provided the right conditions are applied ie correctly rated lamp and depth of tank some harder corals can be kept.
One if the down sides to this style of lighting is that there is no warm up period, meaning the light is either fully on or off another consideration is that they flood lighting to all areas which means the shimmering effect is lost, however they are relatively cheap which can have a bearing on the fixture quality itself (not the florescent tube though), the lamps are usualy good for up to 12 months before replacement, some manufacturers will state burning hours, as an approximation every 4000hours equates to 1 year
As a comparison T5s give approximately 65 lumens per watt where as T2 gives 75 approx lumens per watt making the newer T2 a better light source, that said I've nit really seen them available for aquariums
CFL (compact florescent lighting)PL/PLT PC
These are all forms of what we know as energy saving light fittings in short they are small fluorescent tubes and have similar characteristics to the florescent tubes Some of these however have a built in ignitor making the intial fitting slightly cheaper, the draw backs here are the same as florescent tubes above
MH (Metal Halide)
These lights are widely regarded as the king of lights and up until recently were the only light of choice to keep reef tanks under, there are big advantages of using these lights as they have a great efficacy ie their lumens per watt rating is somewhere around 70-120 which compared to flourescent or CFL of 65 lumens per watt, given this it's easy to see why they are widely used in this environment, another key part to consider is that they have a long warm up time which is approx 10-15min to full temp which is beneficial for all tank inhabitants as it reduces the stress and to a lesser degree helps mimic nature, they are relatively cheap to purchase if you look around and just about every electrical whole saler will either have parts on the shelf or easily available, they tend to come in 4 standard wattages 70w 150w 250w & 400w with each being available in different Kelvin ratings such as 10000k 14000k & 20000k which makes it very adaptable to most environments, draw backs are they do produce a lot of heat, the lamp is really only good for max 1 year, one thing to bear in mind also is that the ballasts for these lights are only compatible with set wattage lamps ie a 70w ballast (the electrics that run the light) will only run a 70w lamp and is not compatible with for example a 150w lamp, they also are fairly power hungry especially the higher wattage setups, another key issue is they don't like hot restrikes, which means that you cant turn the light off then straight back on, as it has too cool before being able to turn back on.
LED
These lights are relatively new technology, and are continuously being developed in order to improve their output, although LEDs have been about for years they have not had sufficient reliability in order to give a constant output, early luminaries were made up of LEDs daisy chained together making the power and voltage reduce the further along the chain it goes, at the time of writing this there are still cheap luminaries that adopt this method although this is reflected in the price as with anything if it seems to cheap to be good it most likely is just that!
Modern luminaries employ a very complex driver/power supply to run which must be incredibly stable, which when considering the ambient temp and conditions can effect these parameters, it's no wonder the higher end more reliable products are initially expensive, at this point it's probably prudent to add a warning to all DIY enthusiasts saying that if your going to build your LED system make sure you research what your doing thoroughly and understand the implications of not doing this right, often I see home made led units where the person who has built it can't understand why their tank looks like its struggling or that growth has slowed or stopped, as stated earlier PAR & PUR are incredibly difficult to measure so home made units cannot easily be proven to be giving out enough light for your system.
Led unlike any other light source has minimal colour variation over time however the lumen output will diminish, typically this will be stated as an L rating if buying a pre built unit, this refers to the lumen depreciation percentage at a given burning hours, for example at 50,000 hours it may be L70 which means that the the lumen output is only going to be 70% at 50,000 hours compared to the 100% when new, this will inevitably lead to problems down the line as visibly you will not be able to see any change in the light output, the first thing you will see is your tank suffering, in homemade units this could occur at any point but you as the owner will not be able to determin if the lighting is up to scratch.
Another problem to bear in mind is led will burn to extinction without any visible (or only minimal) drop in visual appearance so again you have no way of telling when the unit has expired, if you took the TMC aquaray (probably most widely known marine led luminaries) they will give you 50,000 hours life on the LEDs great so approximately 10 years, however they only guarantee the power supply for 1 year, draw your own conclusions from this but my thoughts are that beyond this the driver is not stable enough to maximise output, going back to the L rating their tech department have admitted that they only have a theoretical value of L70 at 50000 hours, why? Simply because there has been no time to fully test them to this life period.
So to sum up pros and cons of led
They are cheap to run with low heat being emitted, the light output can be finely tuned to insure that only beneficial colours are used, they can be fully dimmed (if the luminaire has this option) meaning they can fully mimic dawn and dusk, to some degree they have a good guarantee from manufacturers (on the LEDs only).
On the down side the initial outlay is expensive parts are not readily available and while the longevity of the LEDs themselves is great are the LEDs made to be replaced? Also without Having to annually change the lamp or being able to would you remember in 10 years to take action? Also when the LEDs eventually fail do you have to replace the whole unit?
All this said some of the down sides are still questions without answers.
PLASMA LIGHTING
While this is not yet Currently a fully available light it is worth a mention as this is technology that is becoming a major talking point and is being developed for various applications including aquariums, there are a number of videos floating around on YouTube etc which if you have a chance is worth a look, whats unique about this lighting is that this is a light source that has no physical connection as the halide etc inside the lamp is excited by radio frequency and has a huge amount of output and considering the lamp is the size of a tic tac its definitely worth watching out for!
Lighting maintenance
As a final thought or consideration on lighting a key part of maintaining a well lit aquarium is to replace lamps regularly, by doing this you are insuring that the desired amount and level of light is being maintained not only for the health of the reef/aquarium but to also deter algae from taking hold, it's almost impossible for me to give accurate details on lamp life as different lamp manufacturers will specify different lumen/light depreciation levels, but to give you a very roughy guide any type of flourescent lamp be it PC CFL or T5/T8 you can expect between 6 months to a year, metal halide (Mh) approx 1 year, and LED most likely 10 years plus (although current units are designed to be replaced entirely not just the lamp) most packaging will state burning hours, if in any doubt ask the supplier, manufacturer or post something on here as I'm sure someone will be using the same product and be able to advise.
This article will hopefully give you some information that will enable you to make an informed choice of what best to use In your own environment, I will state before I go any further that this will unlikely give you a definitive answer in what you should use to light your aquarium, simply for the reason that there are normally multiple options that will have similar results. And ultimately it's the hobbiest choice
For those that are new to the hobby I'll give a break down of each of the different types of lighting and some pro's and cons for each, I'll also try and cover a few other considerations that even some of the most experienced aquarists among us may not be aware of.
The old rule of thumb with lighting especially with reef setups was to use x watts per gallon, with light efficacy (efficienacy of light output) improving this rule has really dropped by the wayside, to put this into some context Flourescent light tubes give between 30-90 lumens per watt and MH (metal halide) gives between 65-120 lumens per watt with led surpassing MH lighting with lumens per watt.
So it's easy to see why watts per gallon is no longer really applied, as the results could be dramatically different if applied across the board, for example a 10w fluorescent tube may give out 300 lumens where as a (theoretically as 10w mh to my knowledge doesnt exist) 10w mh lamp could give 650 lumens!
What kelvin lamp?
For the most part people believe that the degree kelvin rating has very little relevance and is purely aesthetic, however this is not so, reefers tend to keep within around 10000K - 20000k with the 20000k being far more blue in colour than the 10000k which is more yellow
The K rating does though have a dramatic affect on your tank and in my opinion ( and this is my personal opinion) is almost equally as important as PAR (which will be discussed later) why? In short and to try and keep it simple blue light is the last colour to be absorbed by water meaning it penetrates deepest, so by putting a higher K rated lamp which has more blue in it you can be sure light penetrates to the darker depths, there are a few pit falls to be aware of though.
One of the biggest things reefers overlook is the depth of thier aquarium in relation to what K lamp works best, below is just a guide and is by no means a definitive be all and end all answer to what works for you as You may decide to use more than one different k rated lamp especially if your using a T5 luminaire.
Tanks 12-20 inches 10000k will strike a good balance of coral growth as well as tank aesthetics
Tanks 15-30 inches 14000k lamps will be a better option as light will penetrate deeper
Over 30 inches 20000k with supplementary lighting to light higher in the water column as this will have Little useable light Which may result in Coral growth slowing
As you can see from above there is an overlap on the 10000 & 14000k lamps so this is to a degree the users choice, these should all be used in conjunction with actinic lighting which is not just for aesthetical purposes as there are photosynthetic invertebrates (clams nudibranch etc) that need this light, as a word of caution 20000k lamps should be used wisely as over 15000k there is very little useable light for corals etc unless it is supplemented with additional light to light the shallower water, but I'm guessing there aren't that many people with 2.5ft deep tank?
PAR (Photosynthetically Active Radiation) and PUR
(Photosynthetically Useable Radiation)
PAR as stated in the title stands for Photosynthetically Active Radiation which is a specific band of light between approx 400-700 nanometers which plants, coral and symbiotic zooanthellic algae require to survive, however while it is important it's only able to be measured using specific meters and more importantly it's not PAR per say that is the crucial element that's required for coral and plants to grow as not all PAR is useable by plants and coral, the part that we should be concerned with is PUR (Photosythetically Useable Radiation) PUR is that fraction of PAR that is absorbed by zooxanthellae photopigments thereby stimulating photosynthesis which we see as coral and plant growth, Without delving too far into this subject which is likely to cause confusion and raise more questions than answers I'll summarise this subject
As PAR meters are not particullarly accurate and PAR is not necessarily useful (led luminaries can emit high PAR but low PUR) and PUR is virtually Impossible to measure (to my knowledge there is no meter available for this) we tend to go back to kelvins as we know from history and test that the light penetration is sufficient to provide ample PAR and PUR it's for this reason that I state Kevin is an important consideration in choosing which light to use
Different Lights
T12, T8, T5 &T2 lighting
Common place at the moment are T5 flourescent tubes, the T indicates tubular and the 12, 8, 5 & 2 all indicate eighths of an inch diameter so a T5 is a tubular 5/8 of an inch diameter flourescent light, coincidentally the longer the tube the higher the wattage.
These lights are usually sufficient to keep soft corals and provided the right conditions are applied ie correctly rated lamp and depth of tank some harder corals can be kept.
One if the down sides to this style of lighting is that there is no warm up period, meaning the light is either fully on or off another consideration is that they flood lighting to all areas which means the shimmering effect is lost, however they are relatively cheap which can have a bearing on the fixture quality itself (not the florescent tube though), the lamps are usualy good for up to 12 months before replacement, some manufacturers will state burning hours, as an approximation every 4000hours equates to 1 year
As a comparison T5s give approximately 65 lumens per watt where as T2 gives 75 approx lumens per watt making the newer T2 a better light source, that said I've nit really seen them available for aquariums
CFL (compact florescent lighting)PL/PLT PC
These are all forms of what we know as energy saving light fittings in short they are small fluorescent tubes and have similar characteristics to the florescent tubes Some of these however have a built in ignitor making the intial fitting slightly cheaper, the draw backs here are the same as florescent tubes above
MH (Metal Halide)
These lights are widely regarded as the king of lights and up until recently were the only light of choice to keep reef tanks under, there are big advantages of using these lights as they have a great efficacy ie their lumens per watt rating is somewhere around 70-120 which compared to flourescent or CFL of 65 lumens per watt, given this it's easy to see why they are widely used in this environment, another key part to consider is that they have a long warm up time which is approx 10-15min to full temp which is beneficial for all tank inhabitants as it reduces the stress and to a lesser degree helps mimic nature, they are relatively cheap to purchase if you look around and just about every electrical whole saler will either have parts on the shelf or easily available, they tend to come in 4 standard wattages 70w 150w 250w & 400w with each being available in different Kelvin ratings such as 10000k 14000k & 20000k which makes it very adaptable to most environments, draw backs are they do produce a lot of heat, the lamp is really only good for max 1 year, one thing to bear in mind also is that the ballasts for these lights are only compatible with set wattage lamps ie a 70w ballast (the electrics that run the light) will only run a 70w lamp and is not compatible with for example a 150w lamp, they also are fairly power hungry especially the higher wattage setups, another key issue is they don't like hot restrikes, which means that you cant turn the light off then straight back on, as it has too cool before being able to turn back on.
LED
These lights are relatively new technology, and are continuously being developed in order to improve their output, although LEDs have been about for years they have not had sufficient reliability in order to give a constant output, early luminaries were made up of LEDs daisy chained together making the power and voltage reduce the further along the chain it goes, at the time of writing this there are still cheap luminaries that adopt this method although this is reflected in the price as with anything if it seems to cheap to be good it most likely is just that!
Modern luminaries employ a very complex driver/power supply to run which must be incredibly stable, which when considering the ambient temp and conditions can effect these parameters, it's no wonder the higher end more reliable products are initially expensive, at this point it's probably prudent to add a warning to all DIY enthusiasts saying that if your going to build your LED system make sure you research what your doing thoroughly and understand the implications of not doing this right, often I see home made led units where the person who has built it can't understand why their tank looks like its struggling or that growth has slowed or stopped, as stated earlier PAR & PUR are incredibly difficult to measure so home made units cannot easily be proven to be giving out enough light for your system.
Led unlike any other light source has minimal colour variation over time however the lumen output will diminish, typically this will be stated as an L rating if buying a pre built unit, this refers to the lumen depreciation percentage at a given burning hours, for example at 50,000 hours it may be L70 which means that the the lumen output is only going to be 70% at 50,000 hours compared to the 100% when new, this will inevitably lead to problems down the line as visibly you will not be able to see any change in the light output, the first thing you will see is your tank suffering, in homemade units this could occur at any point but you as the owner will not be able to determin if the lighting is up to scratch.
Another problem to bear in mind is led will burn to extinction without any visible (or only minimal) drop in visual appearance so again you have no way of telling when the unit has expired, if you took the TMC aquaray (probably most widely known marine led luminaries) they will give you 50,000 hours life on the LEDs great so approximately 10 years, however they only guarantee the power supply for 1 year, draw your own conclusions from this but my thoughts are that beyond this the driver is not stable enough to maximise output, going back to the L rating their tech department have admitted that they only have a theoretical value of L70 at 50000 hours, why? Simply because there has been no time to fully test them to this life period.
So to sum up pros and cons of led
They are cheap to run with low heat being emitted, the light output can be finely tuned to insure that only beneficial colours are used, they can be fully dimmed (if the luminaire has this option) meaning they can fully mimic dawn and dusk, to some degree they have a good guarantee from manufacturers (on the LEDs only).
On the down side the initial outlay is expensive parts are not readily available and while the longevity of the LEDs themselves is great are the LEDs made to be replaced? Also without Having to annually change the lamp or being able to would you remember in 10 years to take action? Also when the LEDs eventually fail do you have to replace the whole unit?
All this said some of the down sides are still questions without answers.
PLASMA LIGHTING
While this is not yet Currently a fully available light it is worth a mention as this is technology that is becoming a major talking point and is being developed for various applications including aquariums, there are a number of videos floating around on YouTube etc which if you have a chance is worth a look, whats unique about this lighting is that this is a light source that has no physical connection as the halide etc inside the lamp is excited by radio frequency and has a huge amount of output and considering the lamp is the size of a tic tac its definitely worth watching out for!
Lighting maintenance
As a final thought or consideration on lighting a key part of maintaining a well lit aquarium is to replace lamps regularly, by doing this you are insuring that the desired amount and level of light is being maintained not only for the health of the reef/aquarium but to also deter algae from taking hold, it's almost impossible for me to give accurate details on lamp life as different lamp manufacturers will specify different lumen/light depreciation levels, but to give you a very roughy guide any type of flourescent lamp be it PC CFL or T5/T8 you can expect between 6 months to a year, metal halide (Mh) approx 1 year, and LED most likely 10 years plus (although current units are designed to be replaced entirely not just the lamp) most packaging will state burning hours, if in any doubt ask the supplier, manufacturer or post something on here as I'm sure someone will be using the same product and be able to advise.
/straylightoptical.com/products/aquarium
