T5 Aquarium Lighting – Suitable For Which Corals?

Aquarium lighting for a reef aquarium is very important. It is second in importance only to seawater quality. The lighting system needs careful consideration if corals are to prosper.

In a fish only system the lighting is not particularly important. The fish need to see and also be seen, that’s all. Two fluorescent tubes¸ one white and one actinic blue are sufficient. Two tubes are required in order to create a ‘dawn and dusk’ cycle. Of course, the aquarist could use more tubes if desired.

For the reef aquarium there are options. The aquarist could choose metal halide lighting¸ which is the most popular at the moment. This popularity is likely to change because halides are expensive to run and give out a lot of heat which can affect the seawater. The light of the future is the LED array though at present these are expensive to buy. They do not put heat into the aquarium and are much cheaper to run. There are also fluorescent tubes which have been available to aquarists for many years, which don’t develop the heat of a metal halide and are again cheaper to run.

Fluorescent tubes have developed over the years – T12 tubes, then T8’s, and then T5’s which are the current type. All types are still available though it is the latter one that is of most interest to aquarists. The numbers 12, 8, and 5 refer to the diameter of the tube.

The development of fluorescent lighting has included spectrum. Aquarists can choose tubes of differing spectrum. For example, a marine white tube will give a spectrum of around 10000K (K=Kelvin which is a measure of colour temperature). White is an important and much used colour in the aquarium. Another is blue actinic which is used by perhaps the majority of reef aquarists.

The reason why colour output is so important is because in the sea colours disappear at various depths – red disappears quickly¸ blue penetrates deeply so the corals are used to certain colours and require them (this is a generality). Within the flesh of most corals kept on a captive reef are zooxanthellae which are single celled algae. These algae require light of the correct type to flourish. This in turn means the coral will be healthy.

T5 tubes could be used for any coral as they can be obtained with the correct colour output. However, there is one more consideration and that is intensity.

Metal halides are powerful and can ‘punch’ light to the bottom of deep aquariums. T5 lights do not have as much ‘punch’ and this is the area where particular care needs to be taken. The aquarist who has decided to use T5 lighting should be aware of this limitation.

If the aquarist wishes to keep hard corals (SPS) then the aquarium needs to be shallow, or at least it does if the hard corals are to cover the reef. A depth of around 12” is probably the limit, though even then the aquarist will have to watch that corals lower down are settled. Not all corals require as much light so those that are happy with less can obviously be placed lower. It is probable that most success will be obtained in the top 6″ or 9″ from the surface.

Most aquarists will not be happy with an aquarium of 12″ or less depth. Most are 18″, 24″ or even more. If the desire is to have an entire reef of hard corals (SPS) then T5 lighting will not do, though blue actinic lighting can still be used.

If the aquarist wants to have a mixed coral reef, that is some hard corals and also soft corals, then T5 lighting could be used. As above the hard corals that need a lot of light will need to be placed in the top 6″ or 9″ from the surface. The rest of the reef can house corals that will accept less light such as many soft corals. Even so, the lower areas will be the place for corals that can settle with low light levels, there is a fair choice. Some aquarists do not like an arrangement as described as it could appear too stratified and unnatural. In this case the choice is really soft corals and those hard corals that can survive without high light intensity, though they will probably still require to be in higher areas of the reef.

Soft corals are generally easier to place, though once again care is needed to ensure that they receive sufficient light.

When fitting T5 fluorescent tubes it is advisable to use reflectors and to fit as many as possible lengthwise. These tubes need electronic ballasts and types that can drive two tubes are available which makes for more convenience. The tubes should be equally divided between marine white and actinic blue. Lay them out white then blue then white etc so that there is a good and even spread of both. If the tubes total an odd number, make the additional one a white. In addition the tubes should be fitted as close to the water surface as is practical to ensure maximum light availability. Creating a ‘dawn and dusk’ cycle is easy, just wire the blues and whites separately and make use of two electric timers.

T5’s are the latest incarnation in fluorescent lighting. The aquarist who makes use of them will have a good choice of lighting tube lengths and colours, and will also know that they are less expensive to run than metal halides. A number of tubes as described when housed in a close fitting hood generate quite a lot of heat so the aquarist should be aware of any effect this may have on seawater temperature, though any problem is not as great as with metal halides.

Success can be achieved with T5 lighting as long as the restrictions, mainly to do with depth of aquarium are taken into account. It is also important to change the tubes every 6 months to a year, the latest being a year. This is to minimize light intensity reduction and spectrum shift.

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Night Time Is Just As Important As Day Time

Most (perhaps all?) life runs to a light and dark rhythm. Humans certainly do, we need our sleep.

Life on the wild reef isn’t an exception. During the day many fish and other life forms are out and about finding food. As soon as darkness approaches they find a safe sanctuary where they can pass the night, as at night other life emerges, much of it predatory.

So life is tuned to a night/day cycle. So it is in the aquarium as the livestock need the cycle to function. I don’t know what would occur to daylight loving stock if the lights were left permanently on, or vice versa, but it isn’t an experiment I’d care to undertake.

Providing a day/night cycle is simple. Let’s start with a fish only system. This system type is not normally lit by metal halide bulbs, but by fluorescent tubes. For the cycle to work there needs to be at least two tubes, one actinic and one marine white. There also needs to be two electric timers.

Each tube is connected through its ballast to a timer. The timers are set so that the actinic tube switches on about ½ hour before the marine white. At the other end of the cycle, the marine white is set to switch off ½ hour before the actinic. The marine white can be left to run between 8 and 10 hours, meaning that the actinic tube will be on 9 to 11 hours. The fish will now wake up to a ’dawn’ and be stimulated to prepare for night at ’dusk’.

The reef system is very similar, except that lighting on a reef system is more critical and more lights will often be present. This does not make any difference to the lighting cycle system though. If a metal halide is in use, then an electric timer will be required for this. The metal halide is the main light for the day period. If marine white tubes are in use, they will need to be connected through one electric timer. If not already present, the aquarist will need to provide one or better two actinic tubes, which need to be wired through the other electric timer. Again, the actinics switch on and off ½ hour before and after the main lighting. The main lighting can again be left on between 8 and 10 hours, again meaning the actinic will be on for between 9 and 11 hours.

The lighting periods suggested above are not critical, and the aquarist can make the timing choice according to the needs of the livestock.

Sometimes it is recommended that the main marine lighting should be on for 12 hours. This recommendation relates to the average tropical day which is circa 12 hours. However, there isn’t a need for intense lighting for this length of time as it doesn’t occur in the tropics. Either side of midday the light is intense, but earlier and later it is less. In addition, the power of the sun cannot be equated in the aquarium.

If a lighting regime such as outlined above is implemented, the aquarist will perhaps be surprised at how quickly the fish ‘learn’, appearing a little after ’dawn’ and preparing for night at ’dusk’.

The lighting regime is also good as it is much more natural than plunging the aquarium into light or darkness, which is bad. The closer to nature’s dawn/dusk environment the system is the more contented the livestock will be.

There is an advantage to the aquarist too. Watching the fish react to lighting changes is one. Using a torch and watching the night life is another, though more for the reef system. The aquarist could be surprised at the amount of life and movement there is after dark.

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Angels Of…?

Here’s a question for anyone who reads this. I have a feeling I have come across this before but just cannot tie it down, and being unable to do so means I cannot answer the question.

The creatures seem to be attracted to light and they are very small. So what are they? Are they dangerous or not?

Have a look at the attached video, and if you have any idea then let us know in the comments facility. Or, if you prefer, by Email.

Here’s the video…

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What Is PAR?

When this topic arose I wondered what to do with it. The reason I wondered is that this website is designed for beginners and ‘earlier-on’ aquarists (though I notice that experienced aquarists are now visiting, and they’re more than welcome). Lighting is a scientific and technical subject.

Most things can be broken down to basics though, and an attempt has been made to do this. In addition, advice is always given to employ the proper lighting, that is spectrum and power, particularly for reef systems. Perhaps a basic explanation of PAR will demonstrate why this is, and is therefore relevant.

There isn’t a requirement to know any more than the need to employ the proper recommended spectrum and power output over a reef. Fish only systems are not so demanding of course, the fish need to see and be seen, and it is good to see the colours reasonably enhanced.

Having the proper spectrum and power output is important, as said. The power output is measured in watts (W), and with metal halide bulbs this requirement depends on the depth of the aquarium. Fluorescent tubes have power outputs generally relevant to their length, though different tubes exist (eg. normal output (NO), high output (HO), and very high output (VHO)). Spectrum refers to the colour of the light, which is of particular importance to the corals, or more correctly a great many of them. The corals that we have in our aquariums for the most part require the correct spectrum.

Generally, corals contain zooxanthellae, or single-celled symbiotic algae. This algae is very important to the coral (see the text ‘Zooxanthellae’). The algae use photosynthesis and need light to do this.

So PAR then. This stands for Photosynthetically Active Radiation. In other words, light that is potentially useful to photosynthesis. It is measured in nanometers (nm).

In the sea, different colours of light are lost, some before others. The first to be lost is red, within a few feet of depth. Blue penetrates deeply, and is the only light left (except UV) after around 50ft. It is blue that is of interest to aquarists. It is stated that blue light of circa 420nm is of good use to zooxanthellae. Thus there are ‘actinic’ tubes and other tubes that are manufactured to peak at this point. Metal halide bulbs can be obtained with different spectrum outputs.

Blue is not the only colour useful to photosynthesis, but it has been found to be useful in a captive system. There are many corals that use this available light and they are usually lower in depth on the reef. There are corals close to the surface and obviously these receive much stronger light and more than just blue. The corals deal with this naturally, as there is much more light available for photosynthesis than is needed.

I reckon that is all that is needed. It really is a ’skim’ over the surface, as said lighting is a complex subject. As with so many things, one thing could be dependant on another, provided that yet another is present. I apologise to any lighting engineers who might see this text, but it is not intended for you.

Us aquarists need only understand what is needed and basically why on the different aspects of keeping a marine aquarium. In this case, it is the lighting that the zooxanthellae can use to photosynthesize, allowing our corals to prosper.

(Ref: Aquarium Corals. Eric H. Borneham)

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Give Me The Moonlight

Our marine aquariums for the most part, whether reef or fish only, are very natural, far more so than they were even just 10 years ago. Technology has advanced a great deal as well.

The lighting is designed to help the corals and also look reasonably natural, the filtration is varied but many, if not most, aquarists use live rock. Live rock is probably the best filtration available and there isn’t any more natural. With efficient – or perhaps a better word is imaginative – aquascaping, the aquarium now really can appear to be a ‘slice of the ocean.’

Most aquarists including myself sit and gaze at their aquarium and marvel at how lovely it is, and at the same time marvel at how livestock from a home such as the reef – connected to the huge volume of the seas and oceans – can possibly survive let alone thrive in a tiny aquarium. But they do.

There is a continuing search for better ways of using nature to improve things. One of these is the deep sand bed (DSB), another very natural way of filtering. The use of macro algae such as Caulerpa is another. There are more examples.

Trouble is, most aquarists have restraints, perhaps financial, or space available or both. I fall into the space category, though finances are not exactly without bounds.

There is one thing I have done to advance my system though. It isn’t unique, a lot of other aquarists have done the same. It doesn’t take up much space and certainly doesn’t cost a fortune, far from it. That last bit is perhaps a little unusual for this hobby!

I’ve given my reef moonlight. It’s very simple to do. This involves the use of LED’s (light emitting diodes). LED’s have been in the news recently as the technology slowly moves forward to challenge metal halides in the power lighting of a captive reef. In this case, that is moonlight, the LED’s have low output.

What I’ve done is obtain a set of four blue LED’s in a very small unit. This has been placed on the top bracing strut – out of the water – at one end of the aquarium. The lights are angled down to shine diagonally through the water. The power comes from the mains supply.

An extra electric timer has been placed in the cabinet below the aquarium. The moonlights do not come on in the ’dawn’ sequence, only at ’dusk.’ The sequence is marine whites off first, 15 minutes later the actinics turn off. 10 minutes before the actinics turn off, the moonlights come on, and stay on for one hour. Of course, the moonlights can be on for as long as the aquarist wants.

Unless an aquarist is experimenting with moonlight and corals, I am not aware of any real advantage to the livestock. The fish and shrimps seem to become accustomed to the main white and main blue lights going off in sequence, and ‘take to their beds’ just before the blues disappear (or mine do). The presence of the moonlights must make the sequence a little less abrupt however.

It is marvellous looking at the reef under full lighting and also just the main blue lighting, as they are both attractive. Under actinics some corals fluoresce and this looks terrific, and the blue colour picks out some coralline and similar.

In addition to the above main lights, if moonlights are used this extends the viewing period and offers a really quite magical scene. LED’s create a ripple effect, and flickering shafts of light shine diagonally through the water, picking up corals and other reef shapes.

So the advantage of moonlights is to the aquarist, offering more viewing pleasure. The icing on the cake is that the cost of these lights is low, the running cost very low, and the life expectancy of the LED’s very long. It cannot get better than that. So go on, indulge.

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Aquarium Lighting Advance

In years gone by aquarists lit their aquariums with tungsten lights. They probably had no idea of spectrum, probably had lots of algae growth, and I would imagine the heat output would have caused problems too. Methods advance.

Nowadays there are two main lighting systems, fluorescent tubes and metal halide bulbs. Fluorescent tubes are mainly used for fish only and soft coral systems, with metal halides lighting mostly hard coral reef systems.

Aquarists have a wide choice of tubes and bulbs, with spectrum being tailored to need. One major ‘fault’ is that to achieve high power output, that is, use metal halide bulbs, there is a premium to pay for electricity. In addition, nowadays we are more aware of our carbon footprint, with all the concern about global warming that has arisen.

Well, the ‘advance’ I’m writing about is not exactly new. I’ve written about it before at some length. The lights are LED’s, which up to now (as far as I am aware) have been available in two forms – moonlight low power and full lighting high power types. It is the high power types that have ‘advanced’.

Up to now the only LED lighting available to light a reef are full arrays, where a high number of LED’s are inbuilt, with different colours incorporated. These arrays come in different sizes for different size aquariums. Trouble is, they are very expensive despite the many advantages they offer (see under Articles and under the sub-heading Equipment – ‘LED Lighting’).

The advance is not so much in technology (as far as I know) but in choice. Power LED’s are coming on to the market which offer choice in much the same way as fluorescent tubes do.

The units which, as said, resemble a fluorescent tube, are a little under 20″ (circa 51cm) in length. They each have 5 LED bulbs and can be obtained as full spectrum, natural daylight, marine white, reef white, marine blue and reef blue. I am not aware at the moment what the difference is between ’marine’ and ’reef’ in the white and the blue. Perhaps one of the blues is the actinic equivalent?

Anyway, with LED’s the aquarist can now ’mix and match’ according to need.

The big drawback, as before, is cost. I understand the light ’tubes’ individually will cost around $175. Ouch! This is tempered however by the cost of running them, which could be as low as around $15 per annum. The lights run at 12v DC. The bulbs are said to last about 50000 hours! The heat output is reported to be very low, so further savings might be made on the cost of a chiller.

The only power output indication I’ve managed to discover is that at 50cm from the aquarium, the LED ’tube’ produces around 33% more light than a 24W compact fluorescent. Fluorescents are usually much closer to the water surface than that, but at a closer point the ratios would remain the same.

I’m hoping for more information particularly on power output. I don’t know if the lights will challenge the supremacy of metal halides yet, maybe the light output close to the water surface will be something like a lower powered metal halide positioned much higher? Hmm. Maybe?

The exciting point is that the LED is still developing and slowly presenting a bigger choice to the aquarist. If the LED now, or does eventually, offer flexible lighting fully suitable to the varied needs of aquarists particularly those with reefs, then metal halides, considering the running cost and heat output, will no longer dominate. Definitely so if the LED price falls somewhat.

I feel fairly certain that in the course of time LED’s will be the light of choice, particularly for reefs, with all the advantages, especially those of running cost and lack of heat into the aquarium. Power output is the thing for the reef – that will come if it isn‘t here already.

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How Do You Know Which Aquarium Lighting You Will Need?

The marine aquarium has two main types, the fish only (FO) and the reef. These systems have a good few things in common, one that is not common to them is the aquarium lighting.

Water quality is the number one requisite in a marine aquarium, and this is closely followed by the lighting (for a reef). The new aquarist can be forgiven for being confused over quite a few areas of marine equipment, and lighting can be one of these.

In the planning stage, the aquarist has decided what type of aquarium to keep. On many (most?) occasions this will be a reef. There are quite a few others who decide on a fish only. This may be because when listing the necessary equipment the cost proved to be too high, or simply that the aquarist intends to gain experience first and/or wants to keep fish that are unsuitable for a reef.

Anyway, the aquarist has made a choice for whatever reason. This makes the choice of lighting easier.

If the aquarium is going to be a FO, then there are only two reasons that lighting is provided – the first so that the fish can see and have a daylight/night cycle and the second so that the aquarist can see the fish. This means two fluorescent tubes that have a suitable colour spectrum for marine. The tubes could be T8’s or better T5’s. One could be daylight and the other actinic. The sole purpose of the ‘proper’ spectrum is to show the wonderful fish colours to full advantage.

The reef system needs more thought, and more money. The fish have the same requirements as those in the FO. The placing of corals in the aquarium is what causes pause for thought.

Many corals (but not all) have symbiotic algae (Zooxanthellae) which are necessary to the corals. This algae, like others, needs lighting of suitable power and spectrum. Failure to provide the correct lighting power, taking into account the depth of the aquarium, and spectrum can lead to problems with the corals. At least a bank of T5 fluorescent tubes running the length of the aquarium, and as many as will fit, taking into account reflectors, from front to back is required. A good mix is half marine daylight and half actinic. If the corals are the soft variety, this may well be sufficient. If they are the hard variety, they may be sufficient if the hard corals are placed in the top third of the reef.

If the aquarium is to be a hard coral reef and perhaps one or two soft types are to be kept lower down, the best current lighting type is metal halide. This lighting is a bulb or bulbs in a reflective canopy, the bulbs being 75 watts (w) up to 400w. It is possible to obtain bulbs which are even more powerful. The bulbs come in a variety of ‘spectrums’, annotated as Kelvin (k). The current vogue seems to be for 14000k, sometimes higher. The higher the number, the more blue, or cold, the light appears. Aquarists often supplement the metal halide lights with actinic fluorescent tubes, in an attempt to ensure that the symbiotic algae receive the correct lighting, and this helps give an attractive appearance to the aquarium.

There is one more check that needs to be made, and that is running costs. Metal halides are quite expensive to run, and along with heaters and/or coolers (chillers) the electricity bill could be substantial. It is worth checking the running cost before making a decision.

Lighting in itself is a complex scientific subject. However, the beginner needn’t worry about this, but just needs to make sure that the lighting chosen represents an acceptable onwards cost to run, and that it is suitable for the intended livestock. There is a great deal of non-technical information available.

Very basically, if running a FO aquarium the aquarist can choose fluorescent tubes. It is probably best to use T5’s, particularly if the aquarium is fairly deep. If running a soft coral reef, fluorescent tubes can be used, but more of them as above. If running a hard coral reef, metal halides (possibly with actinic fluorescent tubes) are better, particularly if the aquarium is fairly deep.

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