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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Tags: Aquarium Lighting, Equipment, marine reef, marine-aquarium, metal-halide, reef-tank

Base Your Lighting On Your Livestock Or Your Livestock On Your Lighting

This article is aimed more at aquarists who are interested in keeping corals. Aquarists who decide to keep a fish only aquarium do not need to concentrate on lighting as much as aquarists who keep corals do. Fish only aquarists need to use lighting to create a day/night cycle to provide an inhabitant which the fish feel safe in and also to make the aquarium more visibly attractive to the aquarist.

In a coral only or coral/fish aquarium it is a different matter. The corals utilise the light to gain much needed energy from the light source. Actually it is not the corals themselves it is the symbiotic algae that live within the coral which use the light and provide the coral with energy.

Very much like a ‘thank you for keeping me safe’ kind of thing.

As with the fish only aquarium there is still a requirement to create a day/night cycle so that the aquarium inhabitants are both not engulfed in light as well as being suddenly plunged into darkness.

The trouble is different corals have different lighting requirements. There are some corals which require very intense lighting and other corals which prefer lower levels of lighting. There are even some corals which do not need lighting and gain their energy purely from feeding. These are called non-photosynthetic corals but I won’t cover these in this article.

Photosynthetic corals receive the majority of their energy from the light and the remainder of their energy from actively feeding. As the corals receive so much energy from light it is therefore imperative that the correct lighting be supplied to them.

Aquarium lighting is quite a large topic due to the various types of lighting available, the different spectrums etc. I am not envisaging this article to cover the different types of lighting available but to hopefully provide a little bit of guidance when it comes to ensuring that the correct lighting is installed for the corals you either have or hope to keep.

There are too many times I hear of people purchasing a coral and then attempting to find out what the corals requirements are or even worse not bothering to find out and then wondering why the coral is not thriving or even unfortunately dying.

It is of my opinion that every single purchase made should be thoroughly researched prior to the decision being made to part with your cash. I do appreciate that this is very hard to do and at times is not even possible.

I firmly believe that there are two options available which are covered in this articles title:

‘Base Your Lighting On Your Livestock Or Your Livestock On Your Lighting’

I will cover these one at a time however it is also important to consider the depth of your aquarium. The reason for this is that the colours of the spectrum in the lighting are stripped out the deeper the light has to penetrate.

The following examples are based upon an aquarium which has a depth of 24″.

Base Your Lighting On Your Livestock

In this scenario you have decided upon the type of corals you wish to keep and now you will need to select your aquarium lighting based upon the requirements of your choice of corals.

It is presumed that the aquarist is still in the research stage and has not actually purchased any corals prior to installing all the required equipment.

In the hard only coral scenario you will need to have lighting which is quite strong and has the ability to be able to ‘punch’ the lighting to the entire depth of the aquarium. In this example I would recommend either metal halide lighting or the new LED aquarium lighting. As said it is important to consider the depth of the aquarium. If you do not consider this and purchase lighting which is not strong enough then the lighting which is at the bottom third of the aquarium may not get enough light and therefore any corals you place in this area will not get enough light.

In the soft coral scenario you will still need to have lighting which is of the correct spectrum however you will not need lighting which is as strong as the metal halide/LED lighting option. The reason for this is that whilst soft corals do still need a good amount of lighting it does not need to be as strong as hard corals require. In this scenario I would recommend using either T5 or T8 lighting.

In the mixed hard/soft coral scenario then you need to be a little more careful. The reason for this is that these two types of corals require different strengths of lighting. The reason why you need to be careful is in relation to the placement of the corals in the aquarium. If you place a hard coral too low down in the aquarium then there is a risk that the coral will not receive enough light. If you place a soft coral to high in the aquarium then there is a risk that the coral may receive too much light and actually could get burnt. In this scenario the recommendation would be that you can use either metal halide, LED lighting or even T5 tubes as long as you can place enough of the tubes in the hood. As said though in this scenario you need to ensure that you place the corals in the correct position so that they receive the correct amount of light based upon their requirements.

Base Your Livestock On Your Lighting

This option is my preferred option as you are able to setup all of the equipment required prior to even considering the actual purchase of a coral however I do appreciate that a lot of people do actually set up their aquarium based upon what they know they want to keep and for this I applaud them.

OK, let’s have a look at some of the lighting options available:

T8 Lighting – With this type of lighting you will need to put quite a few tubes into the hood in order to give good coverage of light. It is recommended that you utilise an even split of white and actinic tubes in order to give a good colour spread. T8 lighting whilst economical do not provide that much power and therefore cannot push the light that far down into the aquarium. For this reason it is recommended that you only consider keeping soft corals with this type of lighting.

T5 Lighting – T5 lights are very similar to T8 lights with the exception that they are slimmer in design and are slightly more powerful. As with the T8 lights it is recommended that you install an even mix of white and actinic to give a good colour spread. At the top of the aquarium (about 6″ inches or so) they have a good amount of power, however further than that they have about the same power of a T8. For this reason you should be able to keep certain types of hard corals in the upper quarter of a 24″ deep aquarium and soft corals under that. Certain LPS (Long Polyp Stony) corals may be suitable to thrive in the mid/lower regions however I would recommend that you check their requirements prior to committing to a purchase.

Metal Halide/LED Lighting – This type of lighting is the most powerful and there are a vast variety available in relation to the power types available. The power as with all lighting is based upon the watts. The higher the wattage the more powerful the lighting is and the further into the water the unit can push the light. Using this type of lighting you should be able to keep both soft corals and hard corals; however you will need to ensure that the corals are placed in the aquarium in a location where their light requirements are met. For example you would not want to put a soft coral at the top of the aquarium as it would receive too much light and could even get burnt.

Conclusion

It is exceptionally important that the correct environment be created for the corals which are being kept. Not just lighting but also water movement and the actual physical placement of the coral.

When in the store looking at making a purchase do not be afraid to speak to an employee of the store and ask if the coral(s) in question are suitable for your aquarium. Inform them of your lighting and they should provide you with the correct information for you to base your decision upon. I say should as unfortunately there are some stores who will just say ‘Yeah, that will be fine’ just so that they can get the sale. The majority of stores are not like this and have a huge interest in the well being of the animals they sell but unfortunately there are some that do this. My recommendation if this happens - walk away and purchase elsewhere.

It should also be noted that proper acclimatisation techniques should always be followed - not just in relation to actually transferring the coral from the shop to the aquarium but also correctly acclimatising them to the light.

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Tags: Aquarium Lighting, aquarium-livestock, coral, Equipment, metal-halide, reef-tank

Have You Ever Looked At Your Aquarium In Natural Daylight?

My aquarium is lit by metal halides therefore the light provided is quite bright. I use 14K lighting as well as supplemental actinics.

Normally the aquarium does not receive any natural daylight as blinds have been installed to prevent this, however the other day whilst I was doing my maintenance my wife opened them to do some cleaning. With it being a bright sunny day as soon as they were opened the aquarium was bathed in natural sunlight. As said my lighting is quite bright but as soon as natural daylight landed on the aquarium I could not even see it. It was totally masked by the sun.

Having a closer look at the aquarium I saw things on the rocks which I have never seen before. It was amazing how different it looked. The rock in particular looked phenomenal and the colours in the fish to me appeared brighter.

I appreciate that the lighting we provide is to emulate the light that the corals receive at a given depth. I believe this is 30M but I am not 100% sure at this moment in time. Obviously in our aquariums they are not this deep so you would expect a difference but I did not expect this amount of difference.

Needless to say the maintenance stopped and I sat staring at various aspects of the aquarium. After a while my wife must have finished cleaning or whatever it was she was doing and shut the blinds. Suddenly I could see the aquarium as I normally see it and to be honest I think I prefer it in natural daylight.

One of the things my Dad wants to try is to keep an aquarium which is lit purely by natural daylight. I personally believe that the aquarium will get a lot of algae but my Dad believes that he can control it.

You never know he might some time get time to try this. If he does you can be sure that we will let you know.

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Tags: aquarium, Aquarium Lighting, Equipment, live-rock, metal-halide, reef-tank

Do You Have To Have Metal Halide Lighting For Hard Corals?

Many reef aquarists see hard corals as the height of achievement and the closest thing to a real coral reef in captivity. This isn’t quite true of course, as parts of coral reefs are dominated by soft corals. Nevertheless, a hard coral reef can be very beautiful, and if the aquarist has selected the corals for shape and colour carefully it makes a stunning picture.

The very first requirement for a successful hard coral reef is seawater quality - it must be high and consistently so. This includes the necessary levels of calcium, alkalinity etc. Water movement must also be appropriate, and hard corals generally prefer considerable movement, more so, again in general, than the soft corals.

The second requirement is appropriate lighting. This should be of the appropriate power, which is measured in watts (W) and also the appropriate spectrum. With spectrum, metal halide bulbs are usually purchased with a Kelvin (K) rating. Kelvin is a measurement of colour temperature. The perceived colour of the bulb will become more blue and colder looking as the Kelvin rating increases. For example, a 6500K bulb will appear more yellow than a 20000K bulb, which will appear more blue, or colder looking. Nowadays, it seems there is favour with the 14000K bulb, though the best Kelvin rating for corals is still argued over.

It should be remembered that the corals harbour symbiotic algae known as zooxanthellae. This algae is important to the corals so it is necessary for it to thrive. Zooxanthellae need light of the correct type so that they can photosynthesise. Current thinking is that blue light of the correct wavelength is needed. This seems reasonable, as much light of other colours is lost as the depth of the sea increases. Blue is nearly the last remaining light at depth and must therefore be available to the zooxanthellae in the natural habitat.

So, getting back to the point. Excluding power LED’s (now becoming more available) which are very expensive, there is really only one other light type that could be useful with hard corals, and that is the T5 fluorescent tube. These tubes come in various spectrum outputs, and the two that are of most interest are the marine white and actinic blue types. They should be fitted with reflectors and as many as possible placed over the aquarium, with an equal number of actinic and white if possible.

T5 tubes can produce the correct spectrum, but there is another problem, and that is light penetration. To be fairly sure that hard corals will be adequately lit, the tubes need to be fitted as close as possible to the water surface, maybe two or three inches away. This is quite safe with the fittings used nowadays. Even so, light penetration may not be adequate to any depth, and the corals could need to be sited in the top third of the aquarium (the top third being subject to the overall aquarium depth of course). Some adjustment of the coral’s position could well be required as time progresses.

It is feasible to have a reef such as described in the previous paragraph, with corals that are happy with less light lower down. If the aquarist selects carefully, then many soft corals could be used, but it is necessary to check that these corals are not going to be detrimental to the hard corals. This is because some corals use weapons such as sweeper tentacles which sting, and some soft corals use chemical warfare.

The metal halide bulb has more power (W) and therefore more penetrative ability. The light produced reaches corals lower down. There are guidelines on the power needed for different depths, to provide light for light loving corals. These are guidelines, not rules:

150W 10″ (circa 25.5cm)

250W 14″ (circa 35.5cm)

400W 22″ (circa 56cm)

While we’re at it, another guideline - a metal halide bulb can light around 36″ (circa 91.5cm) of aquarium, that is, 18″ (circa 45.75cm) each side of its centre. So a 72″ (circa 183cm) aquarium could need two bulbs placed 18″ (circa 45.75cm) in from each end. Again, these are guidelines.

As can be seen, ideally the depth of tank needs to be taken into consideration in the planning stage. There are other factors that can affect light penetration but the above is a general guide. It does not mean that a coral will not grow below the stated penetration point - the growth rate could be slower or the coral could be selected by the aquarist to suit the light conditions. (We’re back to that word again - research.)

Some aquarists fit, and many manufacturers provide, actinic fluorescent tubes to be used with the metal halides. Many aquarists consider it advantageous to do this. There is argument over the necessity of it - what if the Kelvin rating of the bulb is high and into the blue range? However, to my knowledge anyway, the additional fluorescent tubes don’t do any harm and seem beneficial.

There is another point that needs to be mentioned about metal halides, and the word ‘point’ is the point. (Err, I’ll tie myself up soon!) Because a metal halide bulb is a point source for light (a fluorescent tube emits light over its full length), a lovely ripple effect is created within the aquarium, much like the sun would create on the wild reef. There is argument about the importance of this among advanced aquarists, but it is enough to say that it is an advantageous effect, at least it is to me.

Two important disadvantages of metal halides are first, that they are expensive to run, and second, they can overheat the aquarium water. So before a final decision is made, consideration must be given to the cost in electricity and also to the environment the aquarium is subject to. If it is a naturally warm environment, there could be a need to invest in a chiller (seawater cooler) which in itself is quite expensive to purchase and fairly expensive to run.

Overall, the metal halide is the light of choice for a hard coral reef at the moment. As said, fluorescent tubes can be used, with extra care exercised by the aquarist.

Anyone planning a reef aquarium should be aware that the more than probable reef light of the future is the power LED array. This is expensive to purchase at the moment, but the aquarist may wish to check on the current situation.

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Interesting Reading From Across The Blogosphere

Lighting is Complicated
- There are, of course, many different types of coral. At the lowest levels of classification, corals generally fall into two categories: hard or soft. Hard corals come in two varieties, large polyped stony corals (LPS) and small polyped …

How To Change A Fish Only Aquarium Into A Reef Aquarium
- The blue tubes stay on all the time from switch on to switch off, this is because they are not just there to create the ‘dusk/dawn’ effect, but they assist the corals as their light spectrum suits the zooanthellae algae in the coral …

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Tags: Aquarium Lighting, Equipment, hard corals, metal-halide, sps-corals

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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Tags: aquarium, Aquarium Lighting, Equipment, led lighting, metal-halide, saltwater-aquarium

The Metal Halide Reflector - Are They All The Same

Choosing aquarium lighting primarily depends upon what you hope to keep in your aquarium. If you are keeping a fish only aquarium then you can provide effective lighting using fluorescent tubes. If you are hoping to keep a reef tank then the corals you hope to keep as well as the depth of the aquarium will determine what lighting requirements you will need.

The majority of soft corals do very well under fluorescent lighting (T5, T8 etc), however if you are serious about keeping a tank full of hard corals then probably metal halide is the best for you. LED lighting is another alternative however for this post will not be covered.

No matter what type of lighting you choose to use there is one thing which you must be using.

A reflector.

So as the title says are all reflectors the same?

Well yes and no.

Yes in the sense that they all reflect light.

No in the sense that they reflect light in different manners.

Aquarium lighting can be quite expensive to run yet it is a necessity in the aquarium. What you are looking for in a reflector is efficiency.

Basically light is emitted from the tube/bulb which is then bounced around inside the reflector and down into the aquarium for your corals etc to utilise as energy.

If you choose a reflector which is poor in design then it will probably reflect the loght over a large surface area, quite often larger than the surface area of the aquarium itself which results in over spill of light into the room where the aquarium is located. This is wasted energy and is definately wasted electricity which is pouring out into the room.

A reflector which is well designed will allow the light to bounce around inside it and then direct it downwards directly into the aquarium in an evenly distributed manner. This type of design will allow for minimal wastage and an evenly spread of light in the aquarium. This type of reflector is also designed so that the light is reflected around the bulb on its way down into the aquarium rather thank through it.

There are various designs which are used - for metal halides the most common of which are the ‘gull wing’ and the ‘diamond’ design. The ‘gull wing’ design is also quite often used on T5 fluorescents. Both of these types of reflectors allow for good reflection of light around the bulb and down into the aquarium in an even spread.

So the answer to the question is that no not all reflectors are the same. After water quality I believe that lighting is the second most important thing. Why waste it by using a reflector which is wasting a lot of the lighting.

At the end of the day it is expensive and required - get it right and get it down into the aquarium.

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Tags: Aquarium Lighting, Equipment, marine-aquarium, metal-halide, saltwater-aquarium

The Lighting Cycle - What Is It

Our everyday lives are controlled by time. We may not like it but that is how it is.
On the wild reef things are much the same. I know, reef life doesn’t have a lunch hour! What they do have is dawn, day, sunset and night.

Life on the reef is controlled by these changes in light intensity. Daylight fish prepare to disappear into their secure holes when sunset arrives. Night life prepares to emerge. At dawn it reverses.

The instincts of marine life do not change when that life is in a home marine aquarium. The light cycle still dictates to them. In the same way that aquarists wish to run their systems as close to nature as possible (live rock, DSB’s etc), it is very desirable to attempt to copy the light cycle of the reef. Aquarists call this the [tag-tec]lighting cycle[/tag-tec], meaning the actions their lighting system follows as time progresses. The benefit is to fish and other mobile life forms, and also to corals. The changing light also makes aquarium watching more interesting to the aquarist.

So it is obvious that there is going to be a dark period (night), a subdued light period (dawn), an all lights on period (day), and then a subdued light period again (sunset).

There are some very sophisticated lighting systems available that can produce the above ‘out of the box’. However, let’s look at a more typical system in use, one that is perfectly adequate.

The lights provided for the marine life in the aquarium depend on the type of life it is, and could be high intensity from metal halides or lower intensity from fluorescent tubes. It makes little difference; the lighting cycle can be achieved easily with both. If only a metal halide is in use, then it is necessary to purchase one or better two fluorescent tubes, with a spectrum known as [tag-ice]actinic blue[/tag-ice]. These are easily obtained. Some metal halide units come with fluorescent tubes fitted. With a fluorescent tube array, it is necessary for one or better two of the tubes to be actinic blue. The aquarist will also need two electric timers. These also are readily available, and should be of the plug in type.

So, let’s achieve the lighting cycle then. The aquarist knows how long his main lighting period is going to be, usually 9 to 12 hours. It is best that the lights are on when the aquarist is there to see the aquarium, pretty obvious really! Knowing the required lights on period in hours, decide when the lights are required to switch on.

The actinic fluorescents power supply is routed through an electric timer. The timer is set to the lights on time less 30 minutes. In other words, the blue actinic fluorescents will activate 30 minutes before the main lights. The main lights power supply is routed through the other electric timer, and the timer is set to switch on at the point 30 minutes after the actinic fluorescents came on.

At the other end of the ‘day‘, the main lights are set to switch off after the number of hours of the decided upon main lighting period. The electric timer for the actinic fluorescent tubes are set to turn off after a further 30 minutes.

Definitely simple. So the sequence in the lights is blue lights come on, fish wake up, corals begin to inflate, nightlife hides away. 30 minutes later the main lights switch on, and ’day’ is there for the main lighting period. At the end of the main period, the main lights switch off, leaving the blue lights on. Fish prepare to hide in the rocks, and night life begins to become active. Corals begin to deflate. 30 minutes later the blue lights switch off and night has arrived, and will last until the blue lights switch on again at the start of a new ’day’.

Though not necessary, a third electric timer can be added if desired. This controls ‘[tag-self]moonlight[/tag-self]’ lighting (usually a very small array of blue LED’s). This switches on 15 minutes before the blue fluorescents switch off for the night. The ’moonlight’ puts very weak light into the aquarium and enhances the lighting cycle effect further, and in addition makes a very attractive sight for the aquarist. The ’moonlight’ can be left on for 2 hours or more. The cost of running them is very low.

The fish soon learn when night is approaching and can be seen preparing to settle for the period. The same when the blue lights first come on, they peer out of their secure hideaways making sure all is well before venturing out. It works very well, and gives the livestock a reasonable resemblance of lighting changes to match their instincts.

Definitely better than suddenly bathing the aquarium in bright light, or perhaps worse plunging it into instant darkness.

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Tags: Aquarium Lighting, Equipment, marine-aquarium, metal-halide, saltwater-aquarium