How Much Electricity Does A Fish Tank Use? Tips for Calculating Your Tank’s Consumption.

You need to run quite a lot of equipment in a fish tank to keep it clean and healthy. Lights, heaters, air pumps, water pumps, filters, protein skimmers, powerheads, and UV filters all require electricity. Because this equipment must run 24 hours a day, 7 days a week, it can have a substantial effect on your monthly electricity bill!

It is a good idea to find out how much electricity does a fish tank use before buying one. Knowing the amount of energy that various types of aquariums use can help you choose one that fits your electricity budget. This article explores the factors that contribute to aquarium energy use, and how you can calculate your own tank’s electricity consumption. 

How Much Electricity Does A Fish Tank Use?

The amount of electricity that an aquarium consumes depends on a few factors – whether the tank is freshwater or saltwater, the size of the tank, and the types of plants and fish.

The top three things that use electricity in a fish tank are:

  • Lights
  • Heating
  • Filtration

Small freshwater tanks with cold water fish species are the cheapest to run because they do not need a heater, just a filtration system. 

Larger saltwater tanks, with lots of plants and fish, need more specialized equipment and, therefore, consume more power. Reef tanks are by far the least energy efficient and most expensive to run. 

On average, a small (10-gallon) freshwater tank that is heated to 72 degrees F consumes about 150 kilowatt-hours (kWh) annually. 

A medium-sized (30-gallon) freshwater tank running at the same temperature consumes roughly 200 kWh per year. 

A large (55-gallon) freshwater tank heated to 72 degrees F consumes about 300 to 400 kWh annually. 

How Much Electricity Does A Fish Tank Light Use?

Lighting accounts for nearly half of an aquarium’s electricity consumption. The amount of energy that aquarium lighting draws depends on:

  • The wattage of the bulb(s)
  • The type of light bulb – fluorescent, LED, or metal halide
  • How long the light is on during the day

A simple freshwater fish tank without many plants only requires a 15 to 40-watt fluorescent or LED lightbulb.

 A tank with more plants requires more powerful light for the plants to photosynthesize, so you need a 100 to 160-watt power compact or fluorescent bulb. 

Reef tanks need a special type of light. Metal halide bulbs can be anywhere from 150 to 1000-watt, so they consume significantly more electricity than fluorescent and LED bulbs

To calculate how much electricity the lights use in a day, multiply the wattage of the bulb by the hours the light is on every day. 

For example, if you run a 30-watt light for 12 hours every day: 

30 x 12 = 360 watt-hours per day

Divide this by 1000 to get the consumption in kWh:

0.36 kWh per day

How Much Electricity Does A Fish Tank Use

How Much Electricity Does A Fish Tank Heater Use?

How much electricity does a fish tank use to keep the water warm enough for your fish? An aquarium heater needs to run 24 hours a day, so heating is the second-biggest contributor to the cost of running a tank. 

Tropical fish tanks must be heated more than cold water tanks, and the greater the size of the tank, the more electricity it takes to heat the volume of water. Aquarium heaters range in power from 25 to 250 watts. 

To work out how much power a heater uses per year, do the calculation above ([wattage x hours]x1000) and multiply the answer by 365 days. 

Small, 25-watt heaters for 5-gallon tanks can use about 219 kWh annually. A 100-watt heater for a 40-gallon tank can consume roughly 876 kWh per year. A 250-watt heater in a 75-gallon tank can use about 2190 kWh annually. 

How Much Electricity Does An Aquarium Filter Consume?

Compared to lights and heaters, aquarium filters do not consume much power. Generally, filtration systems are between 3 and 50 watts. UV filters consume a bit more – 8 to 130 watts. They need to run 24 hours per day. 

To determine how much power a certain filter system uses per year, multiply the wattage of the pump by 24, divide the answer by 1000 and multiply this figure by 365.


The answer to how much electricity does a fish tank use depends on three factors – heating, lighting, and filtration. All three of these main costs are also affected by the size of your tank. However, by following the guidelines outlined in this article, you should be able to estimate the amount of electricity your fish tank uses.

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