Lighting for Saltwater Aquariums

Your choice of lighting for your saltwater aquarium, like everything else, is dependent on your budget.  However, unlike the absolute importance of efficient water circulation and heating to sustain life in your aquarium, the amount you spend on lighting is dependent on whether or not you want to keep coral in the long run.  

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Do I need expensive lighting?

Your choice of lighting is dependent on two criteria, budget and system type.

If you are planning on running a FOWLR (Fish Only With Live Rock), then buying the most expensive lighting on the market is not a requirement.  Although you can of course!  Saltwater fish require simple, run-of-the-mill marine lighting, nothing special.

On the flip side of the coin, if you would like to run a successful SPS dominant tank then you should be looking at the best lighting that you can afford to bring out the colour you would expect from SPS corals.  

My personal experience with lighting

When I first started in marine, I had decided that SPS was my goal.  My first light purchase was a Chinese model called DSunY.  It’s worth mentioning that a successful SPS tank is determined by many factors and that lighting is just one of them.  

I noticed that it did not matter how efficient my system ran, how perfect my parameters were and how well my corals grew (and they grew very well), they were dull in colour.  Instead of a bright green Montipora plate, it was a khaki colour.  My Rainbow Pocillopora should have had bright green and pink beneath the purple polyps, but it was insipid in colour with brown polyps.

I decided to invest in Radion LED’s and although the corals took a week or two to adjust, the improvement in colour was absolutely astounding. My tank suddenly looked as I had been picturing it.

Fish and lighting

As already discussed above, fish are not overly fussy when it comes to light. As long as you supply marine specific lighting you will be meeting the requirement of the your fish.

Marine specific lighting tends to lean towards the blue light spectrum.  The reason for this is that it minimises the potential for unwanted algae growth in your reef tank.  It is advisable to steer clear of freshwater tropical lighting which includes an excessive amount red in the spectrum.  

Coral and lighting

Unlike fish, coral do rely on lighting.

Within each coral (with the exception of non-photosynthetic coral) live symbiotic algae called Zooxanthellae.  This algae converts light energy into food which they consume, the byproduct of which the coral need to survive. Without the correct lighting, the Zooxanthellae who are responsible for the ultimate colour of the coral, simply cannot produce the striking colours a reefer is looking or.

This also partially explains why when purchasing an SPS coral frag (for instance) the colour may look different in the source tank of the seller to the colour it produces when settled, in your tank.

With the above in mind, your choice in lighting will either be of ultimate importance, or it will not.

Do coral need light at night?

The best answer to this question is to look at what happens in nature itself.  Night is dark and even if there is a full moon, it’s certainly not as bright as it would be in the day time.  There are many things we don’t yet understand about coral and the ocean in general but if we are trying to keep a saltwater aquarium, we should try to mimic nature as best we can.  It is unnatural to keep lighting on overnight.  Not to mention the increase in your electricity bill!

Research has shown that the process of calcification is linked to the day/night cycles (source).  During the day, through photosynthesis, hydrogen atoms that are used for calcification of coral are removed whereas at night, they are built up.   

This would not be possible if lighting in the tank was always on.


Lighting options

Listed below are the most common types of lighting available for saltwater aquariums.  

Fluorescent Lighting

Still probably the most common and widely used by many reefers is fluorescent lighting.  T5’s are arguably the most affordable type of lighting, available in various forms and lengths from any LFS

They do emit a certain amount of heat, which can lead to greater evaporation, and could raise water temperature slightly.  However unlike metal halides and LEDs, they do not create a shimmer in the water.

T5 light intensity does diminish over time and it is recommended that they are replaced every 12 months.

Metal Halide Lighting

Metal halide lighting will provide more intensity than T5 fluorescent lighting, as well as a shimmering effect.  They have more of a direct beam and consequently will create contrasting shadows that appeal to many reefers.

They do produce far more heat than T5’s and are known to raise the water temperature.  This does lead to increased evaporation, and in some cases the plumbing in of a chiller to maintain the correct water temperature.

Metal halides do last longer than T5’s and will not need replacing too often. 

LED Lighting

LED lights are not new to the hobby but it did take them a while to take get a foothold in the market.  Now they seem to be becoming the preferred lighting solution for the majority of reef keepers due to the ease of maintenance.  This, along with their integration with mobile apps and their ability to simulate the rising and the setting of the sun is what makes them such a popular choice.

Running costs due to the low wattage of LED has almost become inconsequential.  Most importantly they have the ability to hold their own against T5’s and metal halide lighting.  Many SPS keepers have fantastic colour and growth under LED light, of course depending on the make, model and water conditions.

The only complaint with LED is shadowing.  Shadowing is essentially the direct light characteristics of the LED causing shadows beneath corals, whereas T5’s cast an overall light that has the ability to minimise shadowing.  Although this shadowing has never been a concern for me using Ecotech Radions, or Red Sea ReefLEDS’s some reefers supplement their LED’s with T5 lighting to dispel the shadowing. The combination of both LED and T5 lighting is known as hybrid lighting.

Unlike metal halides and fluorescent lighting, they do not need to be replaced regularly as they do not lose intensity over time. 

LED brands to consider are:  Evergrow LED Lighting, LEDZeal Lighting, Maxspect Razor, TMC Luminair, Aquaray, Kessil, Echotech Radion and Red Sea ReefLED’s amongst others.

Hybrid Lighting

Hybrid lighting refers to fixtures incorporating both LED and T5 lights, giving you the best of both worlds. The fixture below includes fluorescent bulbs only, however it allows the reefer to choose their preferred LED addition to be added to the mid section of the frame which are bought separately.

Hybrid lighting does not need to be as DIY as the above. There are also brands such as the ATI Powermodule which comes with both LEDs and T5 bulbs incorporated.

How long should you leave your saltwater aquarium lights on?

Typically your lights should run for 11 to 12 hours a day, mirroring the length of natural daylight on the reefs.  

This would include a ramp up period from darkness to light in the morning, and a ramp down period in the evening. You can also choose to include a ‘moonlight’ period to view your corals of activity when the main lights go off. The ‘moonlight’ period could be a few hours, before you go off to bed yourself.

So there you have it!

As mentioned above, my personal experience with top of the range Radion LED’s was amazing.  But when I first got into marine I would never have believed that I would be spending THAT much on lights above my tank.

I can quite honestly say I was very happy with my purchases (I think of them as an investment rather than an expense) and would thoroughly recommend getting top of the range for coral growth and colour.

These have now been changed to Red Sea ReefLED’s and I am just as happy with the result.

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