Overview
There always seems to be a lot of confusion when it comes to choosing a lighting system for a reef tank. Everyone has an opinion, and it can be difficult to figure out what is the best choice for my system. In this post I will share some of my experience with lighting. For my background, I have been in the hobby 20 years or so, and have experience with the common lighting choices in my own reef tanks, T12 Fluorescent, T5 Fluorescent, Compact Fluorescent/Power Compacts (CF/PC), Metal Halide (MH), and LED (Light Emitting Diode).
The purpose of lighting in a reef system is to support cnidarians for the most part. They, like terrestrial plants, utilize light for photosynthesis and like plants have different needs depending on the species. If you were to go to the nursery to buy a plant, you would see each one with a label indicating sun, shade, partial shade or whatever.
It works the same way in a reef tank too. Different cnidarians have different needs, so having a concept of a stocking plan before purchasing a light system will really help. Here is a real world example. The current tank I am building will be a lagoon system. I will be keeping seagrasses, soft (Octo) corals, and LPS (Large Polyp Scleractinians) corals in it. These plants and animals do better under bright, but not the brightest lighting available in the hobby, so I chose a fixture with this in mind. This saves money, both in the cost of the fixture, and in my lowered monthly electric bills. So what you plan to stock the tank with is something to think about before purchasing the light system.
There are three basic systems being marketed today for reef tanks. T5, PC, and MH. There are others such as VHO and LED. I won’t be discussing VHO much at all. VHO used to be very popular, but the hobby has gone another direction and for the most part, VHO is used for actinic supplementation for MH today. They stick around because they really do the actinic supplementation better than anyone else.
LED after all these years I feel are still unproven. I say this after owning a PFO light system. I understand the allure of LED from a technology standpoint, but my experience is that they are really not as bright as they claim, and I did not get the results I wanted with them. My best advice is to stay away from them until they have been proven to work (on someone else’s tanks). Virtually all of the LED companies have gone bust, and in my years I have seen good lighting technologies that could not be adapted to the reef aquarium. Halogens and Mercury Vapor lights come to mind. LEDs may prove to be a winner, but they are not there yet.
Intensity and Penetration
PC, T5, MH. Chances are you will use one of these systems, and when choosing it boils down to how much intensity is needed, how deep is your tank, and how much penetration is required. These three systems have different characteristics, and all can be successful with the right setup.
But intensity, wattage, and penetration are not cumulative. You can not make up for a low characteristic by just adding more bulbs with the same low characteristic. If we were all to go to a football game, and filled Death Valley Stadium to watch Clemson kick USC’s rear, there would be 100,000 of us.
If the lights were to go out, say we all took 1 watt LED flashlights out of our pockets and turned them on. There would be 100,000 watts of light in the stadium, but the field would be dark as the 1 watt lights lack the intensity and penetration to reach the field from the stands.
If 100 fans turned on 1,000 watt lights, you would be able to see the players on the field
If 10 fans turned on 100,000 watt lights you might could play the game
If one fan turned on a single 100,000 watt light, it would be very bright.
This is where LEDs and the Watts Per Gallon Rule can be very misleading.
Power Compact
PC, or Compact Fluorescent. When these bulbs first came out they were a godsend. Some makers called them PC, some CF. Within the hobby PC seems to have stuck; outside the hobby CF is more prevalent, but don’t be confused, it’s the same technology. A curved fluorescent bulb with the terminals at one end. The curving on these bulbs detracts from their efficiency, and also makes them very wide with the result that reflectors are limited in how much they can improve performance. PC bulbs are the least intense of the bulbs in use, and have limited penetration capabilities. This limits their applications within marine reef systems. They work well as actinic supplementation to MH, are great for FW planted aquaria, but for normal to large sized aquaria a PC Reef System would really limit the animals that could be kept. A FOWLR system they would be great on.
Nano systems they work great for as well. A nano tank is smaller, and requires less intense lighting. The small size of a nano keeps everything close to the bulb. Depending on what you are doing with your stocking MH or T5 may work better, but PC does work great on nanos.
Metal Halide
There will always be a place for MH in the hobby. MH produces the most intense lighting, and gives off shimmer which is very appealing. The bulbs come as single ended or double ended, and in 150, 175, 250, and 400 watt sizes.
As a rule of thumb, 1 bulb will cover about 2 feet of the tank. So a tank 24” will be covered by one bulb, a 48” tank two bulbs, and so on. A 36” tank you can go one or two.
For usage, if your tank is 16” deep or so, a 150 is good. 24”, 250; and 30”+ 400.
175 watt bulbs have some drawbacks. They offer only 25 watts more than 150 watt bulbs, but are quite a bit larger, and as a result benefit less from reflectors. With the exception of the Iwasaki 175 watt bulb, which is a darn good bulb, the tests I have seen show a 150 watt bulb produces more light in the tank than a 175.
There are 70 watt bulbs, but these only have a specialized application in pico tanks. I have no experience with pico systems and so will not offer an opinion.
Bulbs also come in spectrum, a color temperature that relates to the color of the light emitted. In aquaria we commonly deal with 6500-20,000 degrees Kelvin. The higher the number, the more blue the appearance. 6500k-14k bulbs are typically used in conjunction with actinic supplementation. 14k-22k bulbs can be the only light source.
The specific ballast comes into play as well. MH is all about the ballast and bulb combination. A specific ballast matched with a specific bulb will give specific results. Change one of these factors, and you get entirely different results. I am somewhat of a noob in this area so maybe someone with more knowledge can chime in.
I will say I really like my Phoenix 14k bulbs.
The bane of MH is heat – MH produces a lot of it. Using MH means you need to have a strategy to deal with heating the tank water. It could be fans, could be a chiller, but you will have to factor the heat in.
One final note – if you ever turn off an MH fixture, and then turn it right back on and nothing happens, don’t panic. Wait a few minutes and try again – the bulb needs to be cool to fire.
T5
T5s are the work horse of the hobby. They are very flexible and have many applications. The best MH systems today come with T5 supplementation, and T5 systems are beginning to hit the market with LED supplementation to produce shimmer. This technology is the most commonly used one today.
T5 means in fluorescent lighting means a straight tubular bulb, with connectors on either end, 5/8” thick. T12 is 12/8” thick and so on. As a side note, PC manufacturers are making claims that their bulbs are T5 PC. This is an outright falsehood in lighting terms, used just for marketing. The T denotes a straight tube, not a curvy one.
T5s are a straight, thin bulb. If MH is all about the ballast, T5 is all about the reflectors. The bulbs being so narrow, it is possible to wrap a reflector around it and focus the light from the bulb directly into the tank. This increases light and penetration as much as 300%.
When choosing a T5 light system, consider only the systems that have individual reflectors for each bulb. The difference in performance like I said is as much as 300%.
Being thin, this also enables us to “stack” more bulbs in a given space, increasing the intensity and amount of light available in the tank. It is very easy to underestimate how much light a quality T5 system can produce.
The stacking of bulbs is really where T5s come into their own. There are many specialized T5 bulbs out there, and you can mix and match them to make the colors on your fish and corals really pop. A UVL 75/25 bulb produces a lot of red. My common firefish glows fluorescent red and orange under this bulb. This gets very complicated, and there are more bulb combinations that work than there are aquarists, and a lot of it comes down to preference.
But some generalities about the bulbs. They come in Purple (Actinic), which are 420 NM (nano meters) in color; Blue (which many are labeled actinic, like Current, but are not) which are 460 NM; and Daylight. Which are around 10k (10,000 degrees Kelvin).
Add into this mixed bulbs, which are a combination of Daylight/Blue, Red/Daylight, and it gets complicated.
As a rule, Daylight bulbs produce more PAR (photosynthetically active radiation, light in the spectra used for photosynthesis, the only accurate measure for the hobby) than the others. Some of the individual combination bulbs counter intuitively produce more PAR than a daylight bulb. And actinic bulbs produce very low PAR. What they do is make things fluoresce.
The mainstay bulb is the ATI Blue Plus. This bulb for whatever reason, is one of the highest PAR bulbs out there. Being a blue bulb, it emits some light in the actinic range, and will induce fluorescing. About half the bulbs in your system should be Blue + bulbs.
Bulbs also come in standard lengths, 24”/24 watts, 36”/39 watts, 48”/54 watts, 60”/80 watts. When we talk T5, we really mean T5HO, because all these bulbs and fixtures are driven for High Output. You can over-drive these bulbs with an Icecap ballast. A 36”/39 watt bulb will become 54 watt; a 48”/54 watt will become 80 watt and so on. This is T5 VHO.
There are also 18” T5 bulbs out there. I really recommend against them. The bulb choices are extremely limited, and they are all cheap Asian manufactured bulbs. None of the good performers come in this size.
Active Cooling is also very important for T5. This means a fan. The cooler the bulb is kept, the more PAR it will emit. For every 2 degrees the bulb reaches over 79 degrees, it loses 1% of its potential output. So, a bulb which reaches 108 degrees, which is common in uncooled fixtures, loses 50% of its output.
For penetration, with a good quality reflector, T5 can do 24” very well. My ATI does 200 PAR 25” deep in my tank, which is better than many MH systems. I think many of the bad experiences come from people who do not use quality reflectors, actively cooled fixtures, or a combination of these. For the tanks most of us have, T5 will work great.
For up to 30”, and ATI or Aquactinics reflector will be just fine, Beyond that, which really is not that common, go MH.
For bulbs, stick with ATI, UVL, or Geisemann. There are individual bulbs out there that may come into play, like the GE 10k daylight or the Koralen Zucht Fiji Purple; but these outperform the other manufacturers for the same price, or just a buck or two more. A Current daylight bulb is around 250 PAR, an ATI daylight is 370 PAR, without reflector.
For fixtures, they commonly come in 4 bulb, 6 bulb, and 8 bulb setups. Aquactinics also makes 5 and 7 bulb setups. 6 bulb setups produce the most PAR. 8 bulbs produce the same par over a wider area
ATI fixtures are of much better quality than everyone else, then Aquactinics, then a number of manufacturers in the pack.
MH versus T5
Don’t let anyone tell you different. For all intents and purposes, MH and T5 are technically equivalent. With very few exceptions, you would not be anymore successful with one of these systems over the other. And those exceptions come down to animals that require expert care, like Ritteri Anemones, and individual animals.
The choice between these two technologies comes down to personal preferences. MH produces shimmer, which is very appealing. T5 doesn’t produce as much heat and can be fun to play with colors. The best coloration in corals I have seen comes from T5; the best growth comes from MH; tastes great, less filling. That’s your call.
Recommendation
If you have no idea what you will be stocking with, or what you like, my recommendation is a 6 bulb T5 system with individual reflectors and fans. I think it is most likely to give you the results you want, and you will avoid having to upgrade later. Want to do a soft coral tank? Run only 4 of the bulbs. Want to move to SPS (Small Polyped Scleractinian)? Use all 6. They come in many price points, sizes, manufacturers, are relatively inexpensive to run, and you probably won’t be kicking yourself in six months and looking to get a new fixture.
There always seems to be a lot of confusion when it comes to choosing a lighting system for a reef tank. Everyone has an opinion, and it can be difficult to figure out what is the best choice for my system. In this post I will share some of my experience with lighting. For my background, I have been in the hobby 20 years or so, and have experience with the common lighting choices in my own reef tanks, T12 Fluorescent, T5 Fluorescent, Compact Fluorescent/Power Compacts (CF/PC), Metal Halide (MH), and LED (Light Emitting Diode).
The purpose of lighting in a reef system is to support cnidarians for the most part. They, like terrestrial plants, utilize light for photosynthesis and like plants have different needs depending on the species. If you were to go to the nursery to buy a plant, you would see each one with a label indicating sun, shade, partial shade or whatever.
It works the same way in a reef tank too. Different cnidarians have different needs, so having a concept of a stocking plan before purchasing a light system will really help. Here is a real world example. The current tank I am building will be a lagoon system. I will be keeping seagrasses, soft (Octo) corals, and LPS (Large Polyp Scleractinians) corals in it. These plants and animals do better under bright, but not the brightest lighting available in the hobby, so I chose a fixture with this in mind. This saves money, both in the cost of the fixture, and in my lowered monthly electric bills. So what you plan to stock the tank with is something to think about before purchasing the light system.
There are three basic systems being marketed today for reef tanks. T5, PC, and MH. There are others such as VHO and LED. I won’t be discussing VHO much at all. VHO used to be very popular, but the hobby has gone another direction and for the most part, VHO is used for actinic supplementation for MH today. They stick around because they really do the actinic supplementation better than anyone else.
LED after all these years I feel are still unproven. I say this after owning a PFO light system. I understand the allure of LED from a technology standpoint, but my experience is that they are really not as bright as they claim, and I did not get the results I wanted with them. My best advice is to stay away from them until they have been proven to work (on someone else’s tanks). Virtually all of the LED companies have gone bust, and in my years I have seen good lighting technologies that could not be adapted to the reef aquarium. Halogens and Mercury Vapor lights come to mind. LEDs may prove to be a winner, but they are not there yet.
Intensity and Penetration
PC, T5, MH. Chances are you will use one of these systems, and when choosing it boils down to how much intensity is needed, how deep is your tank, and how much penetration is required. These three systems have different characteristics, and all can be successful with the right setup.
But intensity, wattage, and penetration are not cumulative. You can not make up for a low characteristic by just adding more bulbs with the same low characteristic. If we were all to go to a football game, and filled Death Valley Stadium to watch Clemson kick USC’s rear, there would be 100,000 of us.
If the lights were to go out, say we all took 1 watt LED flashlights out of our pockets and turned them on. There would be 100,000 watts of light in the stadium, but the field would be dark as the 1 watt lights lack the intensity and penetration to reach the field from the stands.
If 100 fans turned on 1,000 watt lights, you would be able to see the players on the field
If 10 fans turned on 100,000 watt lights you might could play the game
If one fan turned on a single 100,000 watt light, it would be very bright.
This is where LEDs and the Watts Per Gallon Rule can be very misleading.
Power Compact
PC, or Compact Fluorescent. When these bulbs first came out they were a godsend. Some makers called them PC, some CF. Within the hobby PC seems to have stuck; outside the hobby CF is more prevalent, but don’t be confused, it’s the same technology. A curved fluorescent bulb with the terminals at one end. The curving on these bulbs detracts from their efficiency, and also makes them very wide with the result that reflectors are limited in how much they can improve performance. PC bulbs are the least intense of the bulbs in use, and have limited penetration capabilities. This limits their applications within marine reef systems. They work well as actinic supplementation to MH, are great for FW planted aquaria, but for normal to large sized aquaria a PC Reef System would really limit the animals that could be kept. A FOWLR system they would be great on.
Nano systems they work great for as well. A nano tank is smaller, and requires less intense lighting. The small size of a nano keeps everything close to the bulb. Depending on what you are doing with your stocking MH or T5 may work better, but PC does work great on nanos.
Metal Halide
There will always be a place for MH in the hobby. MH produces the most intense lighting, and gives off shimmer which is very appealing. The bulbs come as single ended or double ended, and in 150, 175, 250, and 400 watt sizes.
As a rule of thumb, 1 bulb will cover about 2 feet of the tank. So a tank 24” will be covered by one bulb, a 48” tank two bulbs, and so on. A 36” tank you can go one or two.
For usage, if your tank is 16” deep or so, a 150 is good. 24”, 250; and 30”+ 400.
175 watt bulbs have some drawbacks. They offer only 25 watts more than 150 watt bulbs, but are quite a bit larger, and as a result benefit less from reflectors. With the exception of the Iwasaki 175 watt bulb, which is a darn good bulb, the tests I have seen show a 150 watt bulb produces more light in the tank than a 175.
There are 70 watt bulbs, but these only have a specialized application in pico tanks. I have no experience with pico systems and so will not offer an opinion.
Bulbs also come in spectrum, a color temperature that relates to the color of the light emitted. In aquaria we commonly deal with 6500-20,000 degrees Kelvin. The higher the number, the more blue the appearance. 6500k-14k bulbs are typically used in conjunction with actinic supplementation. 14k-22k bulbs can be the only light source.
The specific ballast comes into play as well. MH is all about the ballast and bulb combination. A specific ballast matched with a specific bulb will give specific results. Change one of these factors, and you get entirely different results. I am somewhat of a noob in this area so maybe someone with more knowledge can chime in.
I will say I really like my Phoenix 14k bulbs.
The bane of MH is heat – MH produces a lot of it. Using MH means you need to have a strategy to deal with heating the tank water. It could be fans, could be a chiller, but you will have to factor the heat in.
One final note – if you ever turn off an MH fixture, and then turn it right back on and nothing happens, don’t panic. Wait a few minutes and try again – the bulb needs to be cool to fire.
T5
T5s are the work horse of the hobby. They are very flexible and have many applications. The best MH systems today come with T5 supplementation, and T5 systems are beginning to hit the market with LED supplementation to produce shimmer. This technology is the most commonly used one today.
T5 means in fluorescent lighting means a straight tubular bulb, with connectors on either end, 5/8” thick. T12 is 12/8” thick and so on. As a side note, PC manufacturers are making claims that their bulbs are T5 PC. This is an outright falsehood in lighting terms, used just for marketing. The T denotes a straight tube, not a curvy one.
T5s are a straight, thin bulb. If MH is all about the ballast, T5 is all about the reflectors. The bulbs being so narrow, it is possible to wrap a reflector around it and focus the light from the bulb directly into the tank. This increases light and penetration as much as 300%.
When choosing a T5 light system, consider only the systems that have individual reflectors for each bulb. The difference in performance like I said is as much as 300%.
Being thin, this also enables us to “stack” more bulbs in a given space, increasing the intensity and amount of light available in the tank. It is very easy to underestimate how much light a quality T5 system can produce.
The stacking of bulbs is really where T5s come into their own. There are many specialized T5 bulbs out there, and you can mix and match them to make the colors on your fish and corals really pop. A UVL 75/25 bulb produces a lot of red. My common firefish glows fluorescent red and orange under this bulb. This gets very complicated, and there are more bulb combinations that work than there are aquarists, and a lot of it comes down to preference.
But some generalities about the bulbs. They come in Purple (Actinic), which are 420 NM (nano meters) in color; Blue (which many are labeled actinic, like Current, but are not) which are 460 NM; and Daylight. Which are around 10k (10,000 degrees Kelvin).
Add into this mixed bulbs, which are a combination of Daylight/Blue, Red/Daylight, and it gets complicated.
As a rule, Daylight bulbs produce more PAR (photosynthetically active radiation, light in the spectra used for photosynthesis, the only accurate measure for the hobby) than the others. Some of the individual combination bulbs counter intuitively produce more PAR than a daylight bulb. And actinic bulbs produce very low PAR. What they do is make things fluoresce.
The mainstay bulb is the ATI Blue Plus. This bulb for whatever reason, is one of the highest PAR bulbs out there. Being a blue bulb, it emits some light in the actinic range, and will induce fluorescing. About half the bulbs in your system should be Blue + bulbs.
Bulbs also come in standard lengths, 24”/24 watts, 36”/39 watts, 48”/54 watts, 60”/80 watts. When we talk T5, we really mean T5HO, because all these bulbs and fixtures are driven for High Output. You can over-drive these bulbs with an Icecap ballast. A 36”/39 watt bulb will become 54 watt; a 48”/54 watt will become 80 watt and so on. This is T5 VHO.
There are also 18” T5 bulbs out there. I really recommend against them. The bulb choices are extremely limited, and they are all cheap Asian manufactured bulbs. None of the good performers come in this size.
Active Cooling is also very important for T5. This means a fan. The cooler the bulb is kept, the more PAR it will emit. For every 2 degrees the bulb reaches over 79 degrees, it loses 1% of its potential output. So, a bulb which reaches 108 degrees, which is common in uncooled fixtures, loses 50% of its output.
For penetration, with a good quality reflector, T5 can do 24” very well. My ATI does 200 PAR 25” deep in my tank, which is better than many MH systems. I think many of the bad experiences come from people who do not use quality reflectors, actively cooled fixtures, or a combination of these. For the tanks most of us have, T5 will work great.
For up to 30”, and ATI or Aquactinics reflector will be just fine, Beyond that, which really is not that common, go MH.
For bulbs, stick with ATI, UVL, or Geisemann. There are individual bulbs out there that may come into play, like the GE 10k daylight or the Koralen Zucht Fiji Purple; but these outperform the other manufacturers for the same price, or just a buck or two more. A Current daylight bulb is around 250 PAR, an ATI daylight is 370 PAR, without reflector.
For fixtures, they commonly come in 4 bulb, 6 bulb, and 8 bulb setups. Aquactinics also makes 5 and 7 bulb setups. 6 bulb setups produce the most PAR. 8 bulbs produce the same par over a wider area
ATI fixtures are of much better quality than everyone else, then Aquactinics, then a number of manufacturers in the pack.
MH versus T5
Don’t let anyone tell you different. For all intents and purposes, MH and T5 are technically equivalent. With very few exceptions, you would not be anymore successful with one of these systems over the other. And those exceptions come down to animals that require expert care, like Ritteri Anemones, and individual animals.
The choice between these two technologies comes down to personal preferences. MH produces shimmer, which is very appealing. T5 doesn’t produce as much heat and can be fun to play with colors. The best coloration in corals I have seen comes from T5; the best growth comes from MH; tastes great, less filling. That’s your call.
Recommendation
If you have no idea what you will be stocking with, or what you like, my recommendation is a 6 bulb T5 system with individual reflectors and fans. I think it is most likely to give you the results you want, and you will avoid having to upgrade later. Want to do a soft coral tank? Run only 4 of the bulbs. Want to move to SPS (Small Polyped Scleractinian)? Use all 6. They come in many price points, sizes, manufacturers, are relatively inexpensive to run, and you probably won’t be kicking yourself in six months and looking to get a new fixture.
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