How Often Should You Replace Aquarium Light Bulbs?

One of the most common questions new aquarium enthusiasts have is how often to change the light bulbs in their setup. The answer depends on the type of aquarium.

Fish-only aquariums need light to simulate a healthy day-night cycle for the fish. Beyond that, the lighting system provides color and aesthetics to optimize fish viewing. You can wait to replace the aquarium light bulbs when they burn out or if algae begins to build up. Or, simply replace the bulbs annually to make sure the fish are never without light when they need it.

Freshwater plant and saltwater reef aquariums require more oversight of the lighting system. In both types of aquariums, specific types of plants and coral require certain color temperature and light intensity.

Your bulb selection will largely be based on the requirements of the plants and coral. Whether you use fluorescent tubes or metal halide aquarium bulbs, the light output diminishes considerably before the bulbs burn out. In addition, color temperature shift occurs during the life of the bulb as the phosphor coating degrades. For these reasons, the light bulbs in both freshwater and saltwater tanks should be changed on a regular schedule to maintain optimum conditions for the plants and coral.

Depending on the type of aquarium bulbs you use, plan on replacing them every six to twelve months. Your exact schedule will vary based on the bulb manufacturer's rated life of the bulb. For instance, many of the aquarium bulbs that we carry have a rated life of 4,500 to 7,000 hours, with varying color temperatures and wattage ratings.

Calculate the hours of day the bulbs will be on to determine a replacement schedule well in advance of the expected bulb burn out, and consider having at least a couple spare bulbs in the event one burns out unexpectedly or begins to diminish in output or quality prematurely.

The quality of light in all types of aquariums is far more important than getting a few extra hours of life out of a bulb. Bulbs that are diminishing in light output or spectrum can negatively impact fish and plant life and health.