An aquarium can be a stunning expansion to any home, and fish can make great pets. But keeping an aquarium can be a bit of work. One important thing to monitor is the nitrate level in the water. Nitrates can build up over time and lead to poor water quality, which can stress or even kill your fish. You can do periodic things to help maintain nitrate levels in your aquarium.

What Is Nitrate?

Ammonia is a typical waste product found in fish tanks, and its byproduct nitrate is present in soil and water. Its primary sources are old fish feed, aquatic vegetation, and fish excrement.

The biofilter in your aquarium is made to convert ammonia, which is highly poisonous to fish, into less toxic forms. Nitrate is significantly more tolerable by fish than ammonia, yet an excessive amount can still be deadly. 

In addition, nitrate could be present in the tap water used to fill the aquarium. Test the water for nitrate before adding it to your aquarium to see whether the levels are exceptionally high.

Consider switching to nitrate-free water sources if your baseline nitrate level is greater than 10 ppm. 

Nitrate Contributing Factors

You can use a nitrate test kit to see if the nitrate levels in your tank are within permissible bounds. There are various fish supplies online that have different aquarium nurturing products. Most fish or pet retailers carry kits that use a straightforward color-coding scheme to assist you in assessing how much nitrate is present in the water. Read the directions while using your equipment as the kit instructions can differ. 

There are four leading causes of excessive nitrate levels in aquariums, usually one or more of them. 

1. Dirty Filters

High amounts of aquarium nitrate are frequently caused by negligence in filter cleaning.

Keep in mind that the material in the aquarium filter only serves to capture wastes, fish feed fragments, and other debris. The dirt is merely out of sight, but it continues to increase the nitrate load of the water until you clean or replace the media. 

2. Overfeeding

The most frequent cause of elevated nitrate levels in aquariums is overfeeding. Overfed fish make significantly more waste than usual. When given more fish food than they can consume, the leftovers decompose and create even more waste. 

3. Plant Decomposition

Even though tank plants are natural filters that can assist keep nitrate levels low, their dead leaves will decay and produce more waste if not removed. Even healthy developing plants can shed stems or leaves, which can collect on the bottom.

4. Overcrowding Aquarium

Having so many more fish in a tank causes waste accumulation issues. More fish cause more waste. Most aquariums have far too many fish, and high nitrate levels are a common issue.

Many aquarists recommend calculating how many fish you believe you can fit in your aquarium and then putting only half of that number in. It is usually better to keep your tank understocked. However, you may locate yourself with plenty of fish. You must either get rid of a few or get a huge tank. 

How to Preserve Aquarium Nitrate Level

Nitrates in an aquarium can be reduced using various methods and procedures. Dissolved nitrate will be removed by nitrate-absorbing filter media and anaerobic denitrifying biofilters. They will, however, do nothing to address the root cause of the problem. An easy approach is to change the water. When you release a volume of water from your aquarium, all the nitrate in that volume is released.

So, change half of the water and eliminate half of the nitrate. Before you get your hands dirty and completely clean your aquarium, remember that the transition from polluted water to fresh water can be just as damaging to your fish as the nitrates themselves. Water chemistry changes might physically startle your fish. 

Slowly start if you have a high nitrate level. Vacuum the substrate lightly until no more than 15% of the water is gone. Continue cleaning the substrate once daily, going deeper into the gravel, and eliminating approximately 10 to 20% of the water. Continue testing, and after the nitrate level hits 5 to 10 ppm, set up a maintenance plan to maintain it there. 

Keeping your aquarium nitrate level low is essential for a healthy environment. Learn how to do this every step carefully.

Maintain the Aquarium's Hygiene

Keeping the aquarium clean is essential to controlling nitrate levels. The waste eventually produces nitrate; clean tanks have less nitrate that water changes must remove. It means you'll spend fewer hours each month doing maintenance on your tank!

Additionally, a clean environment helps stress fish out and reduces their chances of developing diseases. Regularly taking care of your aquarium will also make it look nicer—and help maintain the Nitrate level.

Regular Maintenance

Feeding your fish should be in moderation. Assure that they finish their meal in two minutes or less. Rather than feeding your fish a large amount of dried fish food once a day, try providing them smaller amounts twice a day. Keep your aquarium from becoming overcrowded.

If cautious feeding results in excessive nitrate levels, you most likely have too many fish for your setup. Every day, perform a short inspection. Remove potential decomposition sources, such as discarded food, dead fish or invertebrates, and dead or dying plant leaves and stems. 

Aquarium Plants Filtration

Since plants absorb most of the ammonia, nitrite, and nitrate produced in the aquarium, a thickly planted tank is the most natural approach to have low nitrate levels. This idea underlies the cultivation and harvesting of macroalgae in saltwater sump systems. When some algae are regularly removed from the system, wastes once present in the water are permanently removed. 

Mangrove plants are particularly well-liked by marine fishkeepers, but they are also helpful for cleaning up garbage in freshwater. These plants have roots in the water but need to emerge from it. Remember, plants can only utilize that waste to a certain extent. So planted tanks, such as reef settings, are often only lightly supplied with fish. 

Controlling the nitrates in your aquarium requires effort. But you'll be thrilled to see healthy, handsome fish swimming happily in a tank in your living room. It'll transcend the effort needed to ensure the health and lifetime of your fish. 


It is essential to maintain a stable nitrate level in your aquarium. It can be accomplished through regular water changes, a quality filtration system, and avoiding overfeeding. Following these simple tips, you can keep your fish happy and healthy for years.