What Are the Best Ways to Lower Nitrate Levels in Your Aquarium?

August 24, 2022
August 24, 2022 Cermedia

As an aquarium and fish owner, it’s no surprise that you want to provide the best possible conditions for your underwater pets. Aquarists and hobbyists alike are always searching for ways to ensure their pets are thriving in the right conditions—ones that will promote healthier, longer, and more vibrant lives. One of the things you’ll need to do from the start, however, is to make sure your nitrate levels are appropriate for the tank and your underwater inhabitants. Allowing nitrates to spike in your fish tank can cause several issues for your pets. Not only can high levels of nitrates hinder the aesthetic of your tank by making it look unkempt with problematic amounts of algae, as nitrates are a nutrient for algae. It can also cause a wide number of health problems for your fish in both fresh- and saltwater tanks (including split fins, fading colors, and balance disturbances). Nitrates can also be very detrimental to the growth and health of corals.

Algae on aquarium wall

Algae growing on the glass of an aquarium.

Keeping all of this in mind—whether you are setting up a brand-new tank or revamping an old—properly maintaining the nitrate levels in your home aquarium can be one of the single most important steps to caring for your aquatic environment.


Here are some of the best ways to reduce the nitrate levels in your aquarium and keeping it healthy for years to come:


Perform routine water changes


Changing out your water frequently—typically 20% to 50% of the water every month in an established system—will help reduce the levels of nitrate in your tank. How often you’ll need to do this can vary depending on the type of fish you keep, how well your tank is maintained, the effectiveness of the biofiltration established and what type of filtration media you’re using. Over feeding or an over-populated aquarium can also affect the frequency of water changes, as these types of action will cause faster increases in the levels of nitrates. Other than reducing the fish load or the amount of food you are feeding (which you should be doing appropriately as well), this simple act of swapping out older water for new will remove these excess nitrates so they don’t become an eventual problem.


Add nitrate-reducing plants


One amazing way to reduce or keep your nitrates at an acceptable level is by adding aquatic plants to your aquarium. Not only Aquatic plants will add to the beauty of your tank, but they will conveniently use nitrates as a fertilizer.


In a freshwater aquarium these can include (but are certainly not limited to!):

  • duckweed
  • frogbit
  • moss balls
  • water sprite
  • water wisteria


In a saltwater aquarium:

  • Mongrove
  • Chaeto
  • Red Gracilaria Algae
  • Mermaids Fan Algae

    Mangroves and freshwater fish

You can also keep a side tank or a refugium, which is useful for growing nitrate-loving algae called chaeto (Chaetomorpha linum or crassa). This macroalgae is known to be a quick grower and quite hardy. Additionally, after the algae absorbs the nitrates, it can be harvested, taking the nitrates along with it.

One thing to keep in mind is that aquatic plants tend to grow quickly and have a large need for phosphates and nitrates. Which means that some maintenance is needed to keep your aquatic plants alive. For example, trimming, dosing carbon and potentially adding even more fertilizer. But mainly, making sure to remove any dead plants or leaves, as they will break down and add nitrates to your aquarium as it breaks down, which can reverse any nitrate-removal progress you’ve made.


Use a protein skimmer


Protein skimmers, also known as foam fractionators, can be added to your tank. The purpose of a protein skimmer is to remove proteins before they can break down into ammonia and nitrates. These skimmers are typically cylindrical shaped chambers that trap the proteins in a brownish foam and collects them, discharging them outside the tank.


These essentially help eliminate any excess buildup of proteins and other organic matter, like fish waste, dead plants, and uneaten food.


Add items that support anaerobic bacteria growth


While most people will talk about adding aerobic bacteria to their aquarium (the bacteria that requires oxygen to break down organic matter turning ammonia into nitrite and then nitrite into nitrate), there are other bacteria that will take the Nitrogen Cycle one further step, converting nitrate into nitrogen gas. These amazing bacteria that helps complete the nitrogen cycle (where nitrogen can safely escape the tank into the atmosphere), are called anaerobic bacteria (bacteria that thrive in the oxygen-free crevices of your tank.) This denitrification process will occur automatically when the proper conditions are in place.


Some ways to help with fostering a healthy anaerobic bacterial load include:


  • Deep sand beds: a fine sand that is layered about 3 to 6 inches deep (the deeper the layers, the less oxygen there will be). Note:  Deep sand beds are often problematic to the aquarium when they are disturbed.
  • Live rock: a naturally occurring ocean rock obtained by either taking it directly from the ocean or mined from a now dry seabed and cultured in an established tank. Live rock contains deep pore structures, which, as water flows into the rock, oxygen is used up, developing anoxic regions.
  • Denitrators: or bio-filtration media, (similar to live rock) which provides enough deep crevices for anaerobic bacteria to proliferate. Some filter media, such as MarinePure®, contains vastly more porosity and surface area than live rock, hence a larger capacity for more anaerobic bacteria to grow.


Keep in mind that while some aquarium owners add the bacteria to their tank for nitrate removal, others prefer to provide the needed circumstances for the anaerobic bacteria to grow naturally. For example, when your tank is cycling naturally (from ammonia to nitrite, and nitrite to nitrate), all the beneficial bacteria your tank needs will begin to grow on all the surfaces and crevices of your tank. This will also create an environment where the right type of bacteria flourishes and if you’re constantly adding new bacteria into the tank, chances are, the bacteria you want to flourish will be competing with the types that will die off anyway (i.e., your tank doesn’t need them and it’s an added cost you don’t need to take on).

In short, if you set up your tank with all the right elements, these processes happen organically, therefore bacteria can be added only as an emergency measure.

Learn More About CerMedia and MarinePure®


CerMedia LLC, located in Buffalo, New York, manufactures MarinePure® Bio-Filter Media.  MarinePure is a man-made ceramic bio-filter media that has the unique combination of a high surface area plus network of open-flow pores. These features enable water to move easily throughout the part, allowing the nitrogen components to find both the aerobic and anaerobic bacteria, allowing all parts of the nitrogen cycle to take place, including ammonia and nitrite elimination and nitrate reduction.

MarinePure PODs

If you have any questions about how to access MarinePure® Bio-Filter Media or incorporate into your new or current tank, feel free to reach out to us. We’d love to help walk you through how to use this bio-filter media for a cleaner, easier-to-manage fish tank.


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Contact us to learn more about how MarinePure and BioVast can help your aquarium and aquaculture environments!


P.O. Box 600
66 River Rock Dr.
Buffalo, NY 14207

info@cermedia.com or

(716) 549-6600

Leyda Vazquez
Business Development Manager
(716) 549-6600 x264

Paul Pustulka
General Manager