Too much nitrate in the aquarium: What you can do - Triops Galaxy

Too much nitrate in the aquarium: These are the consequences of too much nitrate (NO3) in the aquarium

The nitrogen compound nitrate (NO3) is present in every aquarium. In the aquarium, nitrate is the last link in the degradation chain of nitrification in the nitrogen cycle. In contrast to nitrite (NO2), nitrate is much less dangerous for the aquarium inhabitants. In a functioning ecosystem, the nitrogen cycle serves to decompose and transform organic loads. Microorganisms decompose organic material, animal excreta, dead plant parts and food remains are decomposed by bacteria. The bacteria transform ammonium into nitrite and then nitrite into nitrate. Nitrate (NO3) is the end product of the nitrification chain. Nitrate is a natural fertiliser, so too much nitrate in the aquarium will lead to an algae problem. In this article you will learn all the important information about nitrates to make your Triops breeding a success.

Too much nitrate in the aquarium: How is nitrate formed?

Nitrogen in the form of nitrate is an important nutrient for aquatic plants. If growth conditions are good, nitrate is consumed by the aquarium plants together with other elements. It is quite possible that in a heavily planted aquarium the nitrate consumption is so high that it has to be added extra via the nitrate fertiliser in order to counteract growth disorders in the plants. Ammonium (NH4) and ammonia (NH3) get into the water through organic waste such as food or water plant remains, excrements and dead animals. Ammonium and ammonia are converted by bacteria to nitrite (NO2), a toxic substance in high concentrations. In the further stages of the cycle, nitrite is converted to nitrate by bacteria. The nitrate is then absorbed by the aquatic plants as fertiliser. But too much nitrate in the aquarium should be avoided.

Nitrate in the aquarium: Too much nitrate in the aquarium is a warning signal

Although not directly dangerous, a too high nitrate level in an aquarium is a warning signal that should not be ignored. If the aquarium is in balance, the plants absorb the nitrate and any excess is eliminated by regular partial water changes.

The following reasons are responsible for too much nitrate in the aquarium:

  • Few aquatic plants
  • Slow growing plants
  • Poor aquarium maintenance (too few water changes)
  • Weak filter performance
  • Overfeeding
  • High stocking density
  • Tap water rich in nitrates.

What is the ideal nitrate value? In an aquarium with fish and plants, the nitrate level should be between 0 and 50 mg/l. If the value is above this, appropriate measures should be taken to keep the nitrate in the aquarium under control.

Reducing nitrate levels: These measures should be taken

1. Partial water change

If there is excessive nitrate in the aquarium, the first measure is a water change with low-nitrate water. The nitrate levels are quickly lowered, but this approach is not a permanent solution. The values will rise again.

2. Insert aquatic plants

To combat too much nitrate in the aquarium, dense planting should be provided. Plants are an important part of the ecosystem in an aquarium and generate additional oxygen. This benefits the tank inhabitants, plants and nitrifying bacteria.

3. Reduce stocking

Nitrate is often found in tanks that have many animals and sparse planting. Here you should make sure that the stocking in the aquarium is not too high and that the number of aquarium inhabitants fits the size of the aquarium.

4. Use filter media

To permanently reduce nitrate levels that are too high, high-performance filter media can be used instead of regular partial water changes. These help to remove the nitrate from the water. A distinction is made between biological filtration and ion exchangers.


This article covers the basics of nitrate in the aquarium. You can, of course, delve deeper into the subject and expand your knowledge. It is important to know what nitrate and nitrite are and how they differ. A basic understanding of the nitrogen cycle is also essential for every budding and experienced aquarist. Sooner or later you will need and be able to apply this knowledge in your breeding.

Good luck with your breeding!

Sladjan Lazic

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