Saving energy (and money) is always easier when you know how much you’re using. But because many of our smaller appliances draw little amounts of power, we often discount how their combined impact contributes to your home’s energy usage. With our “How Much Energy Does This Appliance Use?” series, we’ll examine what’s watt to learn approximately how much they use.
Aquariums can be a delightful addition to a home, offering a colorful exhibit of aquatic life to provide hours of entertainment for family and guests. But because fish tanks are self-contained environments, maintaining their life support system round the clock, all year long can eat up a significant chunk of energy, with a commensurate impact on your electricity bills.
How Much Energy Does an Aquarium Use?
There are three primary factors that affect what components an aquarium needs, and therefore how much energy it requires:
- The size of the tank. The average sized aquarium is roughly 30 gallons, or 30” long x 12” wide x 18” deep. The larger the tank, the more work your pump and other equipment needs to perform.
- The kind of fish and their environmental needs. Fresh water tends to have more oxygen dissolved in it than salt water. Consequently, salt water aquariums have slightly different water filtration, circulation and maintenance needs to keep those fish thriving. Certain species of fish may need a heater to survive, as well.
- Whether there are plants in the tank. Plants make the aquarium environment more interesting and healthy for the fish, but require the right amount of lighting in order to grow.
How Much Does a Fish Tank Cost to Run?
To calculate how much our aquarium is costing us in utilities, we have to add up the power consumption of the different components, assuming we’re on a fixed-rate electricity plan at 10¢ per kWh.
- We’re going to choose a 190 gph pump running at 19 watts, which is powerful enough to move the water and still provide adequate flow rate for the filter and UV lamp. Since 19 watts per hour x 24 = .456 kilowatt-hours (kWh) per day, this comes to 3.68 kWh per month and 164.16 kWh each year, for a cost of $16.42 annually.
- Our heater works out as 150 watts per hour x 24 = 3.6 kWh per day, 108 kWh per month, and 1,296 kWh each year for a cost of $129.60.
- Our UV lamp requires 5 watts per hour x 24 hours = .12 kWh per day, .36 kWh every month, and 43.2 kWh per year for a cost of $4.32 per year.
- Lighting will come from a standard 2-watt T8 fluorescent. A cheap timer can help reduce the energy consumption, so we’ll estimate that the lights are on 66% of the time or 16 hours of the day. At 20 watts an hour x 16 hours = .32 kWh per day, that comes to 9.6 kWh each month, and 115.2 kWh a year for a cost of $11.52.
In total, that brings your estimated yearly electricity consumption to 1641.6 kWh, which will cost about $164.14.
The main energy thief here is obviously the heater. If we omit the heater, our otherwise identical tank will use about 150-200 kWh per year, or $15 to $20. Just remember, it’s your choice of fish and how you design their environment that will make the biggest splash in your wallet.
Aquarium Pump Power Consumption
Depending on the size of your tank and the type of pump you use, your aquarium pump could use between 3 and 20 watts.
To keep our fish happy and healthy, we need to make sure the water is clean, aerated and maintained at a constant temperature 24 hours a day. That means we need the right kind of pump. Generally, about 6 gallons per hour is the recommended filtration rate, so for our 30-gallon tank, we need a pump that can move at least 180 gph.
There are two basic kinds of pumps: air and water. Air pumps make bubbles that float to the surface and move the water, mixing air and bringing in oxygen. Air pumps run about 3 watts, making them a great solution for small tanks, but in larger tanks over 18-24 inches, resistance to air pressure makes the air pump use more energy. Aquariums (and ponds) over 50 gallons using larger air pumps will run about 6 watts.
Water pumps (including power heads) create currents and aeration, while moving water through various peripherals like filters, skimmers, and heaters. They come in several flavors:
- Submersible pumps can be submerged, but don’t generate the waves we need for aeration. In that case, we would also want a wave pump to help aerate and circulate the water.
- Inline pumps are outside the tank. Far more powerful than submersible pumps, these are connected via tubing to filters, heaters, chillers, etc.
- There is also the pump-filter combo that hangs on the side of the tank pumping water through the filter and using a venturi to mix air and water to create the surface turbulence that aerates the water.
Because water is heavier than air, water pumps require more robust motors than air pumps. Water pumps that fit within the flow rate for our 30-gallon tank typically run between 11 to 19 watts or so. With the exception of a heater, aquarium pump power consumption is going to be your tank’s largest drain on your electric bill.
Heater, UV Sterilizer, and Lighting Energy Use
Depending on what lives in your tank, you may need more electric parts than just a pump and filter.
- Water heaters help keep water at the proper temperature, 72° F to 82° F (depending on the fish type), with a minimum fluctuation of 1-2 degrees over a 24-hour period. A rule of thumb is that it takes 3-5 watts per gallon to maintain water temperature, depending on the room’s ambient temperature. Naturally, the lower the room’s temperature, the more heat the aquarium requires and the higher the wattage. If our room is at 68°F, it will take 102 watts per day to keep the 30-gallon tank heated at 72° F. To keep it heated to 82° F, it will need 170 watts a day. We’re going to stay with 72° F, so a 150-watt heater will be more than adequate for the job.
- UV sterilization lamps come after the filtration section. These kill all sorts of free-floating green water algae, parasites, and harmful bacteria. Lamp wattage depends on tank size and flow rate. In our case, we’re looking at one rated between 3 to 9 watts, as the UV lamp runs continuously.
- Lighting can be an energy headache depending on the wattage. A basic T8 fluorescent lamp uses between 17 to 24 watts depending on the color temperature and lumen output. If you plan on having plants or corals, you want to provide enough light to keep them growing and healthy — which will require better-quality lighting that shines between 8 to 12 hours per day. A good rule of thumb is 2-5 watts per aquarium gallon, but this also depends on the needs of your plants. The deeper the tank, the brighter the lamps will need to be and the higher wattage it will require. These lights usually have a higher lumen output and, depending on the bulb type (halogen, fluorescent, or LED), they can put out significant heat, which may require using a fan or water chiller to keep the water at the proper temperature. We’ve got a couple of plants in our somewhat shallow (18”) tank, so we’ll go with a 20-watt T8 fluorescent.