What are nitrates in an aquarium?

​What are nitrates in an aquarium?

Nitrates and phosphates in aquarium water are parameters that can scare novice aquarists. Indeed, even if you try to maintain your water very carefully, you are not immune to unpleasant surprises. So what are nitrates? And how to react if they are too present in the aquarium?

What are nitrates in an aquarium? Where do they come from ?

Nitrates come from two oxidation reactions which are the result of the transformation of ammonia and the much more toxic nitrites. These nitrates are a source of pollution, because the algae and the zooxanthellae of the corals feed on them.

In addition, the water used to fill the aquarium may also contain nitrates. In France, the rate of nitrates in tap water differs depending on the region. Before filling your tank with water, it may be worth testing it first to find out if the levels present are normal or too high.

In the same way, rainwater is not suitable for aquariums, because it is too loaded with pollution, which it retains during its fall in the atmosphere.

What nitrate level for his aquarium?

In natural environments, the concentration of nitrates is very low. Thus, it is very important to maintain a nitrate level of 40 mg/l maximum in your freshwater aquarium. If you keep shrimp or control algae blooms, keep nitrates even lower (below 20 mg/L).

What is the effect of nitrates on fish?

In the presence of high nitrate levels, fish can experience stress, become more susceptible to disease and have difficulty in reproducing.

A high level of nitrate is particularly harmful to fry and young fish. Indeed, it negatively affects their growth. Also, high nitrate levels often lead to lower oxygen levels, further stressing the fish. Thus, we advise you to follow our recommendations in order to lower the nitrate level of your aquarium if necessary.

What should I do if my aquarium water test indicates too high nitrate levels?

Your aquarium looks clean, your corals have their polyps open, and you don't see any warning signs. But your aquarium water test shows too high a nitrate level? Do not panic !

Some measures can keep nitrate levels low:

• Maintain your aquarium frequently;
• Reduce the amount of food (overeating triggers excess nitrate and other unwanted waste products, such as phosphate);
• Change the water in your aquarium (regular water changes significantly reduce the overall level of nitrates in the aquarium).
• Add live plants (aquatic plants absorb nitrate);
• Invest in a special filter, called a denitrator (preferred solution if the problem occurs repeatedly).

Finally, remember that if your tap water is rich in nitrates, it is best to use demineralised water or reverse osmosis water. These fluids allow nitrate levels to remain low during water changes.

Need more tips to maintain your freshwater aquarium and take care of your biotope? Quickly discover all our other articles dedicated to the aquarium hobby!