Lowering Nitrates In A Freshwater Aquarium

Last Updated on September 11, 2021 by admins

If you own fish, lowering nitrates in a freshwater aquarium is likely something you will have to do. High nitrates levels are a common problem in freshwater tanks. However, high nitrates can be problematic in your aquarium.

It is important to know how to lower nitrates, as they can be potentially harmful to your fish. Fortunately, it can be easy to identify what is causing high levels of nitrates in freshwater and then lower them. Maintaining nitrates is an important aspect of tank maintenance.

What Are Nitrates?

Nitrate is a by-product of ammonia, which commonly occurs in fish tanks from waste. It is a colorless, odorless gas that can build up over time. Nitrates can come from waste, excess food, and decaying plants.

Since ammonia is highly toxic to fish, the biofilter in your aquarium works to break it down into components your fish can tolerate better. However, even though fish can handle nitrates better than ammonia, high levels can still cause problems.

High levels of nitrates in fish tanks can lead to excessive algae growth. This can in return cause the water to become green. Removing nitrates from an aquarium is important to keep the environment healthy.

What Causes High Nitrates In Freshwater Tanks

There are several aspects that can lead to high nitrates in freshwater tanks. When nitrates are too high, it can cause stress for the fish. This makes them more suspectable to disease and can even cause reproduction problems.

In addition, high nitrates can stunt the growth of young fish. Fortunately, there are tests you can buy to test the nitrate levels in your aquarium.

Typically, nitrate levels should be less than 20 ppm in your fish tank. However, it is best to keep the nitrate levels below 10 ppm. It is a good idea to regularly test the nitrate levels in your aquarium to ensure the water is safe.

Broken Filter

A broken filter can lead to all sorts of problems in a fish tank. Over time, nitrates can build up from the gunk in your filter.

 how to remove nitrates from aquarium water

Decaying Plants

Decaying plants can have a negative effect on your water as they break down. As they are decaying, they produce high levels of nitrates.

Lack Of Plants

Plants are an important aspect of freshwater aquariums. Live plants use up excess nitrates for food and growth.


Over-feeding can be a problem for the water in your tank. The leftover food begins to dissolve and can then cause increased levels of nitrates.

Too Many Fish

Too many fish in your tank can be problematic for many reasons. Having too many fish can overwhelm your aquarium. The excess waste from the fish can cause nitrates to elevate as your filter won’t be able to keep up.

Tap Water

Run-off from fertilizer, along with other wastewater,  sometimes leach nitrogen into the tap water. The higher levels of nitrates in tap water can cause issues in your aquarium environment. Many experts will recommend against using tap water as it can include things that can be harmful to your fish.

Not Cleaning The Tank Or Changing The Water Enough

Not cleaning your tank enough can allow the nitrate levels to increase. In addition, not regularly changing the water can cause the nitrate levels to grow.

 how to reduce nitrates in a freshwater aquarium

Read more about: What Makes Aquarium Water Cloudy?

How To Remove Nitrates From Aquarium Water

Maintaining the nitrate levels in your tank is key to keeping happy and healthy fish. If your water tests positive for high nitrates, there are many ways you can lower the levels.

Knowing how to get nitrates down in an aquarium will help reduce stress levels in fish. High nitrates can be particularly detrimental to young fish.

Keep Your Aquarium and Filter Clean

Keeping your aquarium and filter clean will help keep your nitrates at a safe level. You should aim to clean your tank on a weekly basis and keep up regular maintenance on your filter. When cleaning the filter, be sure to use aquarium water in order to maintain the healthy bacteria that is beneficial to your tank.

Regularly Change The Water

To help rid your aquarium of water, you should regularly change your water. Aim to change your water once a week, Be certain to only change 30% of the water at a time.

Add Live Plants

Live plants help utilize the nitrates in your aquarium. In addition, they also provide a hiding place for your fish. Adding living plants to your fish tank can help create a healthy and interactive environment.

Avoid Over-Feeding and Over-Populating

In order to not overwhelm your aquarium with excess food and waste, avoid over-feeding and over-populating your tank. It is important to keep a proper balance in your tank.

Nitrate Filters

Most pet stores sell nitrate filters to help maintain healthy levels in your tank. The filters are available in rocks and pouches. In addition to reducing nitrates, they also help reduce nitrites and ammonia.

Lowering Nitrates In A Freshwater Aquarium

Knowing how to reduce nitrates in a freshwater aquarium is important in order to keep a clean tank. High levels of nitrates can lead to stress, reproductive issues, and even stunted growth in fish. Ideally, you want to keep the nitrate level at 10 ppm or below and no higher than 20 ppm.

Nitrates occur naturally in fish tanks as they are a by-product of ammonia. It can come from waste, leftover food, and decaying plant life. Though fish can handle nitrates better than they can handle ammonia, high levels are still problematic and should be addressed.

The most common causes for high nitrate levels are a malfunctioning filter, too much food, over-population, decaying plants, tap water and not regularly cleaning or replacing the water. Fortunately, there are several ways to lower nitrates. The most common ways are adding live plants, avoiding over-feeding and over-population, regular cleaning, replacing the water often, and nitrate filters.

Do you have any questions on lowering nitrates in a freshwater aquarium? If so, please ask any questions relating to nitrate levels in fish tanks in the comment section down below.

Learn more about: How To Reduce Nitrites In An Aquarium

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