When should you change your reef aquarium bulbs?

by Owen James

Marine Depot has just posted a pretty comprehensive guide to when you should change your reef aquarium light bulbs.

Author Keith MacNeil points out that:

Corals have an alga called zooxanthellae within their tissue. When the zooxanthellae photosynthesize, it produces enough sugar to not only feed the zooxanthellae but the coral as well. To do this properly, they require the proper spectrum of light as well as the proper intensity.

The spectrum and intensity of your light bulb(s) will fade over time. Often this change is subtle enough that the human eye cannot detect a difference.

It is quite the contrary for the organisms requiring light to survive.

So when should you change your bulbs? The answer depends mainly on what bulbs you have fitted.

Macneil suggests the following is a good rule-of-thumb for bulbs.

Bulb Types                  Life of Bulb
Normal Output Fluorescent    6-12 months
Very High Output (VHO)       6-12 months
Power Compact (PC)           9-12 months
T5 High Output (T5HO)        9-18 months
Metal Halide                 9-12 months
LED (non-moonlight)          ~5 years (50,000 hours)

There’s loads more good advice on what other variables can affect the lighting, so do go check out the full article for more information.

Bulbs change reef lighting economics

The need to change bulbs frequently can really change the economics of your lighting set-up, depending on what you’re keeping and what sort of rig you’re using.

With the drop in pricing for replacement metal halide bulbs in the past few years, for instance, what was once the most expensive lighting option can work out cheaper than normal flourescents, or even T5s, when bulb changing is taken into account.

The new expensive kid on the block is being sold partly on the strength of its low-running costs and long bulb life.

LED units cost around £150 here in the UK for a two-strip 24-watt unit that it’s claimed will last for ten years.

Not only do those watts count for far more than normal flourescent bulb output, but LED enthusiasts reckon the unit will pay for itself within 3-5 years if electricity prices stay high.

Check out Katy's Tropical Fish Guide for more aquarium info.

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{ 2 comments… read them below or add one }

Jason 05.20.09 at 4:32 pm

We are running a promo on the Phoenix 250 watt Metal Halide bulbs if anyone is interested. Here is the link:


Might save some folks some money if they are planning on replacing their lamp anytime soon.

jeffry j. johnston 12.01.09 at 10:04 pm

Thanks for the article mention and link! :-)

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