How to Lower Nitrate Levels in a Fish Tank

The impact of nitrate in the aquarium is perhaps less understood by fish keepers than the influence of ammonia and nitrite.

High levels of nitrate in the water can have a detrimental effect on fish and the aquarium environment over time.

For this reason, it’s very important the concept of nitrate and how to manage it is understood by all fish keepers.

In this article, we’re going to look at what nitrate is, the dangers it poses to fish, and how to keep levels under control.

So, let’s get started.

What Is Nitrate?

Nitrate is the final product of the nitrogen cycle.

In an aquarium, it is created when ammonia is converted into nitrite, and then nitrite is converted to nitrate.

High levels of nitrate can indicate that the aquarium is not being cycled properly, or that the filters are not working adequately.

Where Does Nitrate Come From?

As we mentioned, nitrate is produced when ammonia and nitrite, which are byproducts of the nitrogen cycle, break down.

Bacteria known as Nitrosomonas convert ammonia to nitrite and then bacteria named Nitrobacter converts nitrite into nitrate.

Although both of these bacterias can raise the nitrate levels, they are required for the nitrogen cycle to run properly.

What Does Nitrate Do?

Nitrate is not toxic to fish in the concentrations typically found in an aquarium.

However, it can have a number of negative effects over time.

It can reduce the ability of fish to absorb oxygen from the water, leading to fatigue and even death.

It can also reduce the ability of fish to fight off infection, and can promote the growth of harmful bacteria.

In extreme cases, high levels of nitrate can cause the development of algal blooms, which can lead to a decrease in water clarity and an increase in the overall temperature of the aquarium.

How to Manage Nitrate Levels

Fortunately, there are several ways to manage nitrate levels in an aquarium.

1. Remove some of the water from the tank and replace it with freshwater

This will dilute the nitrate levels and make them less harmful to the fish.

2. Add a filter that will remove nitrate from the water

There are many different types of filters available, so it is important to select one that is appropriate for your tank.

3.  Add plants to the tank

Plants can help to absorb nitrate from the water, which will help to keep the levels low.

4. Control feeding amounts

Excess nutrients and other pollutants, such as phosphate, are produced by overfeeding.

If the levels of these substances are kept low, it will help to reduce the amount of nitrate in the water.

5. Monitor the water temperature

If the water is too warm, it will promote the growth of harmful bacteria and algal blooms which will lead to an increase in nitrate levels.

Make sure to keep an eye on the temperature and take steps to cool the tank if necessary.

6. Install a Refugium

A refugium is a location that supports an abundance of animals far from the home.

A refugium, which is a separate environment in which macroalgae may be grown, is a component of an overall nitrate control strategy for marine and reef aquariums.

Macroalgae are highly efficient in removing nitrate and phosphate from the water as it travels through the refugium, lowering levels that would be harmful to your livestock.

You simply remove the algae or seaweed crop and the nitrates with it on a regular basis.

7. Use Microbes

In nature, there are many different types of microbes that play a role in the nitrogen cycle.

Some of these microbes can be used in an aquarium to help reduce the levels of nitrate.

However, it is important to read the packaging carefully before adding any type of bacteria to an aquarium.

Some types of chemical filter media can be used to remove nitrate from the water.

What Are the Effects of High Levels of Nitrate?

The effects of high levels of nitrate in the water are not as immediately deadly as ammonia or nitrite, but it does have an impact on the health of the fish and the aquarium in general.

Nitrate can cause a lot of issues like :

  • A condition called “nitrate poisoning” can be fatal to fish.
  • Loss of color in the fish, and can reduce the growth rate of the fish.
  • Infertility in the fish leads to the death of the fry (baby fish).
  • High levels of nitrate can also encourage the growth of algae in the aquarium.

What Is Nitrate Desired Level?

The desired level of nitrate in an aquarium will vary depending on the type of fish that is kept.

Some fish, such as marine fish, can tolerate higher levels of nitrate, while other fish, like freshwater fish, cannot.

It is important to do some research on the type of fish that you keep and find out the desired level of nitrate for that particular species.

In general, a level of 10-20 ppm is considered safe for most fish.

The Potential Dangers of Excess Nitrate Levels

Excessively high levels of nitrate can have a number of negative consequences on your aquarium’s ecosystem.

The Potential Dangers in the Fish

When nitrate levels reach 100 ppm, particularly if they stay there for lengthy, fish will be affected.

This stress drives fish to become more susceptible to disease and makes it impossible for them to have offspring.

Furthermore, similar circumstances that produce higher nitrate levels also result in decreased oxygen levels, which further stress the fish.

Many juvenile fish and fry will not develop properly, and many will die.

The Potential Dangers in Algae and Other Plants

The presence of high levels of nitrate in the water will encourage the growth of algae.

Not only does this make the aquarium look unsightly, but it can also lead to a decline in the health of the plants in the tank.

Algae compete with plants for nutrients, leading to a decrease in plant growth or even death.

In severe cases, the algae can completely cover the tank and block out light, essentially choking the plants.

High levels of nitrate can also cause harm to invertebrates and corals in a saltwater aquarium.

Nitrate Poisoning vs. Nitrate Shock

Nitrate poisoning and nitrate shock are two separate conditions that can be caused by high levels of nitrates in the water.

Nitrate poisoning

The most typical reason for a fish tank to be in poor shape is neglecting maintenance, overstocking, overfeeding, or a combination of all three.

The consequences of nitrate poisoning are generally fish mortality, with juvenile and marine fish being particularly vulnerable to low levels of nitrate in the water.

Only one or two fish may become poisoned in cases of nitrate poisoning.

However, if you don’t test the water, the cause of the fish’s sickness might go undetected until more fish succumb and eventually fish death begins.

Depending on the fish species, your fish may die for a few days to a few weeks.

Nitrate shock

The term “nitrate shock” refers to the quick exposure of fish to a high quantity of nitrate.

This can happen when:

  • If fish are exposed to a rapid, significant drop in nitrate levels, the same problem may arise.
  • If new fish are added to a tank that contains an abundance of nitrate. Because existing residents have become gradually conditioned to their surroundings over time, the fish are shocked by the poor water quality even if it does not affect them.
  • If you induce nitrate shock by performing significant water changes on a tank that has already accumulated a lot of nitrates, the abrupt decline in nitrates will surprise your fish.

Nitrate shock is frequently deadly to fish, and most times the problem is discovered too late for owners, so you must be careful.

Last Words

The bottom line is that testing your water and keeping nitrate levels low is important for the health of your fish.

Not only will it help to prevent nitrate poisoning and nitrate shock, but it will also keep your aquarium looking clean and healthy.

Regular water testing and maintenance are the keys to a successful tank.

We hope you have found this article helpful.

If you have any further questions, please don’t hesitate to leave us a comment.