Simple Steps to Improve Your Aquarium’s Water Efficiency


Fish may not be the most eco-friendly pets. According to the California Energy Commission, an aquarium run 24 hours per day can use more energy than your refrigerator. Another concern is where your fish were sourced: Were they caught in the wild or bred in a tank?

Plus, fish tanks require regular water changes to keep the tank clean and the fish healthy. So how much water does a tank use? And what can you do to make your own tank more water efficient?

Eric Reinhard is part of the Aquatic Services team for Doctors Foster and Smith, and has nearly 20 years of experience in the aquatics industry. Some aquarists recommend changing 10 to 15 percent of your tank’s water each week. If you replace 10 percent of a 35-gallon tank each week, that’s 182 gallons each year. Reinhard suggests replacing 25 percent of your tank’s water once a month. Over the course of the year, that saves 77 gallons of water.


Keeping the water clean between changes may help to prolong the amount of time between each change. Here are some tips to make your tank even more water efficient:

  • Clean your tank frequently: Uneaten fish food and fish waste turns into pollution within the tank.
  • Add additional filtration. “Filters are a lot more efficient than they used to be,” said Reinhard. He suggests adding live plants – which consume the fish waste – or additional filters that go on the back of or under the tank.
  • Consider the population of your aquarium. According to Reinhard, most people tend to overpopulate their tank, which means more fish producing more waste.
  • Put a lid on your tank to prevent water loss by evaporation.
  • Pour in a bacteria additive that consumes the fish waste.
  • Add fish that are low-waste producers. Reinhard suggests community fish like tetras and platies, which are typically less wasteful, whereas cichlids are the biggest waste producers.

After you change the water in your aquarium, water your indoor houseplants with the dirty water, which is rich in nitrogen and phosphorus. While it’s efficient to reuse that dirty water, it can only be used on indoor plants. The water may contain harmful microbes or non-native bacteria, which you don’t want to introduce into your local water system.

Images: Melody, Art Poskanzer