The Rage for Aquaria

Most freshwater aquarium setups include fluorescent lighting, a filter, and an aerator. The three basic types of aquarium filters are:

• Canister filters--large plastic canisters that have a powerful pump that forces water through a dense filter medium at high pressure.
• Power filters--plastic cartridges that fit inside the aquarium. Water is drawn into the filter by a pump and allowed to trickle back into the tank.
• Under-gravel filters (UGFs)--aerator creates a current that draws water through a gravel filter and up a pipe.

Energy Use in Three Typical Types

Our prototypes' energy usage barely approached that of a microwave oven. Nevertheless, sometimes the loads can be much higher.

Table 1. Comparison of Aquarium Energy Use*
Tank Category	Capacity (Gallons)	Energy Use (kWh/yr)
Small	10	90-120
Medium	30	160-200
Large	55	280-400
* Values are based on use of one or two 10W-20W fluorescent light tubes with 10 hour per day run times; 4W-15W filters with 24 hour per day run times; and 1.5W-4W aerators with 24 hour per day run times.

Sea Water and Plants Can Be Demanding

Some hobbyists go for a lush plant growth in their tanks. These densely planted tanks need extra lighting. A small tank will use 20 watts of lighting (approximately 2 watts per gallon), and the annual total energy consumption will range from 110 to 140 kWh. Medium tanks will require nearly 60 watts and will use 300 to 340 kWh per year. The lighting requirement of a large tank is more than 100 watts, and energy consumption will range from 570 to 650 kWh per year.

Coral Reefer Madness?

The typical reef setup uses a tank and gravity-fed sump combination. After the water flows down to the sump, a powerful pump returns it to the main tank. Another pump pulls water through a protein skimmer, removing amino acids, lipids, phosphates, and other nutrients needed by algae. Reef hobbyists also like to use power heads, which they frequently control with a wavemaker. Because corals do best when water surges in different directions, the wavemaker turns power heads on and off to recreate turbulent reef conditions.

Reef tanks use an average of 6 watts of lighting per gallon, which, in combination with the pumps, frequently creates tank temperatures well above the tropical temperature of 75°F. As a result, the tanks generally need cooling rather than heating. Cooling is often achieved with fans located below the lights that blow air across the water increasing evaporation and cooling the tank. Sometimes, a small air conditioning unit called a chiller is attached to the tank. The fans are relatively inexpensive and are cheaper to operate than the chillers (chillers are rated at approximately 1,800 watts); they are thus the favored option among hobbyists.

During the summer, the fans may run all day long. In other months, they run only when the lights are on. Some reef hobbyists have also been known to run the house air conditioning unit to keep room temperatures low.

So how much energy does a reef tank use? We compared two prototype tanks, a 55-gallon and 180-gallon tank, using typical setups. We found that the 55 gallon tank used around 3,000 kWh per year, while the 180-gallon tank used over 6,000 kWh per year. To put these numbers in perspective, the energy used by the smaller tank was greater than the energy used by a typical home's central air conditioning system and lighting combined. Energy used by the larger tank was greater than the energy used by a typical home's central electric heating and refrigerator combined.

Reef tanks, such as the one pictured here, have circulation, lighting, and cooling needs that can make them a household's single biggest energy consumer.

Something's Fishy Nationwide

These numbers clearly indicate that auditors need to take careful stock of aquarium energy use. That's no fish story!

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