Aquarium With Fish and PlantsCredit: Laura Nubuck, via

You can always can find some nitrates in a typical fish tank. That's nothing to worry about, unless their level is rising too fast. Abundant nitrates pose a risk for your tank creatures. Certain types of fish and all shrimp species are very sensitive to high levels of nitrates. What can you do, when nitrates in your aquarium rise too quickly? Remove them more efficiently, or stop them from increasing so fast. What are the common sources of nitrates in your fish tank?

How to control sources of nitrates in fish tank

There's the nitrification cycle: ammonia to nitrites to nitrates. So, the more ammonia is produced, the faster nitrates form. Do you see the pattern? This process saves your critters from poisoning, as ammonia is very toxic. Ammonia forms from the fish poo, any rotting food and organic matter.

Avoid overfeeding your fish and invertebrates

When you overfeed fish, shrimps or snails, they never manage to eat all the food you throw in to the tank. After a few hours, this stuff starts to rot. That means a transformation to ammonia and other organic substances, which attract algae as well. Therefore, limit feedings to once, or twice a day and offer a handful of food, which would be eaten within a few minutes.

Avoid overstocking your aquarium

Majority of nitrates in your aquarium are produced from fish droppings. What can you do about that? High levels of ammonia frequently mean, that you have overstocked a fish tank. Too many critters in an aquarium can lead to more serious problems,  such as fish diseases, a bad odor, or sudden critter deaths, as well.

Certain fish have a fast metabolism and excrete a lot, for example - goldfish. These animals need the large tank, to avoid a quick build up of excrements in the tank water.

Remove rotting plant matter from your fish tank

Other sources of ammonia, which is transformed to nitrates, are dead critters and rotting parts of the plants. To avoid a fast creation of nitrates, clean the mulm from the bottom of your tank, sucking it outside. Observe the plants and remove their parts, which look unwell. Otherwise they would fall off and decay in a fish tank.

What is the first sign, that you have problems with rotting organic matter in your aquarium? The attack of algae, which are stimulated by organic substances, which are excreted during the process of decay, provides a useful hint.

Remove dead critters from aquarium

When nitrates spike very fast in your fish tank, consider a possibility, that a critter has died. Search your aquarium carefully for the dead body and remove it immediately. Remember, that it could have been a large snail, as well as a fish. There's a chance, that other inhabitants already ate the corpse. In such a case, high level of nitrates is the only sign of the missing creature - unless it managed to jump out from your tank.

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Fix or remove dangerous tank decorations

Do you have an artificial decoration, unstable rock structures or a background, which is installed inside of an aquarium? Check, if any decaying parts, critters or mulm are getting stuck inside or behind these features. Clean up immediately and remove, or fix an offending item, if that's the source of the rising level of nitrates. Otherwise, the problem will return, resulting in another nitrate spike.

Identify other sources of nitrates in a tank

Do you have little children? There's a chance, that kids wanted to feed your fish and have thrown in something inappropriate, like a steak or sandwich, to the container. The cloudy water hints at this possibility. Remove the offending stuff quickly and explain to the child, why that was a bad idea.

Finally, there's a possibiliy, that your tap water contains nitrates. You can learn this information from your water provider. Unless you use a reverse osmosis water filter, you have to keep in mind, that in this case it's necessary to reduce NO3 more efficiently. How can you do that?

How to remove nitrates from aquarium

You reduce the level of nitrates during partial changes of your tank water. Notice, that you need to perform these changes, even if you have no problems with nitrates. The fresh water dilutes unwanted substances, while providing a new dose of minerals.

Add living, floating aquarium plants

Live plants absorb nitrates from the water and use it for chemical processes. Many plants prefer feeding on ammonia instead. That helps as well, since less ammonia means less nitrates down the road. To reduce nitrates efficiently, use a fast growing, aquatic flora. Stem plants are fine for this goal. However, their growth can be limited by an insufficient light, or the lack of carbon dioxide.

For best nitrate removal, use floating plants, such as pistia or limnobium varieties. They drift just under the lighted cover and use CO2 from the air, where its supply is virtually unlimited. This type of plants devours nitrates in the blink. What if NO3 spikes dangerously high and you can't troubleshoot it quickly? Throw in the floating plants from your other aquariums and change water very often.

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Consider fish tank with deep sand bed

In the anaerobic (lacking oxygen) environment live certain types of bacteria. They can transform NO3 to N2, which is a harmless, atmosferic nitrogen. That happens, if you a have a deep sand bed with anaerobic zones in your fish tank. It is a valid solution, which allows for the less frequent aquarium maintenance. However, you should care for your fish tank differently and face new challenges with this method.

Build DIY denitrator

Some DIY geeks build a denitrator. This is an external device, in which the reduction to an atmosferic nitrogen happens without problems, which can be experienced witth deep sand bed. Consider this solution for a large tank with aggresive fish, which destroy any live flora. Never build a denitrator, when you have the planted aquarium. It does it's job too well and reduces nitrates so effectively, that your plants starve.

Construct DIY hydroponic filter

Is your fish tank located close to window, where your indoor plants reside? You can build DIY semi-hydroponic system, in which plant roots come out of the pots into the gravel. Install a small pump to circulate the water from your aquarium through this gravel. The plant roots absorb NO3 and other substances, as the fertilizers. That works, if you use only those plants, which can tolerate a hydroponic cultivation technique.

Try other methods to reduce nitrates

Are there any fast and easy methods to reduce nitrates in fish tanks? Maintaining the balance in the aquarium ecosystem provides more stable environment in the long run. However, there are few methods for a quick fix. Some suppliers recommend mixing NO3 absorbing pearls with the gravel on the bottom. They work up to a year, than lose the absorbtion properties. While they pose no harm, it's impossible to remove them from the gravel.

Use the zeolitic filter medium to reduce nitrates in a fish tank. While this won't deal with a huge spike, it can help an quarist to control the level of NO3. There are liquids, which are advertised to remove the nitrates from the aquarium. While they can aid troubleshooting in an emergency, avoid using them frequently. It's not an economic solution for your fish tank. Besides, invertebrates occasionally react badly to such chemicals, even if they are supposed to be totaly safe.

Avoid overstocking and overfeeding your fish tank and clean up decaying organic matter. Perform frequent partial water changes and introduce fast growing aquarium plants. When you know how to reduce nitrates in fish tank, you can easily troubleshoot, when you discover high levels with your nitrates test kit.

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