Signs of High Nitrates in an Aquarium

Fish are some of the most colorful and exotic creatures on earth. With the proper setup, taking care of these beautiful pets will be an enjoyable hobby and an easy task. There are many different species to choose from and so many ways to customize your aquarium for optimum results. Fish tanks provide a natural setting for your pet with reduced stress and added enjoyment for you.

high nitrate in aquarium

Note: There are several factors that can disrupt any environment. Improper water parameters can lead to poor health, higher mortality rates, and shorter lives for your fish.

Low oxygen levels can result in stunted development or deformed fins or even outright suffocation. Higher nitrate levels in the aquarium may lead to lower oxygen concentrations which inhibit growth and reduce or eliminates breeding activity in young fish.

Here are the basic signs of high nitrates in an aquarium

  1. Dull coloration
  2. Sluggish movement of the fish
  3. Weak immune system
  4. Resistance to feeding

General convention dictates that nitrate concentrations should not outstrip 20 ppm. Better still, 10 ppm is even appropriate.

In order to determine if your fish are being poisoned by high nitrates in the aquarium, it’s important to do regular water tests. Every two weeks is usually enough but depending on how often you do water changes and how many fish you have you may need to check more frequently. It helps to learn the symptoms that indicate something is wrong with your fish so you don’t wait until something happens before you take action.

What are nitrates and why do we monitor them?

The nitrogen cycle is a biological process where nitrates (NO3-) or ammonium (NH4+) are converted into other forms of nitrogen. The most common form of nitrogen in aquariums and aquaculture is actually not the gaseous N2, but instead, the salts dissolved in water as NO3- and NH4+. These two compounds may cause stress to fish in aquariums and so it is important to control them.

Nitrite and nitrate sound very similar and are often confused, but nitrite is very toxic to fish even in small quantities, while nitrate is less toxic and over time, it builds up.

A nitrite level of just 1 ppm (part per million) is enough to kill most fish, but in some cases, the nitrite levels can be up to 200 times higher. There are some cases, where nitrates rise, pH drops, and all newly introduced fish go into shock and die, despite negative ammonia and nitrite tests. Nitrates can also be present in tap water, so you may unknowingly introduce nitrates when you replace the old tank water with the new one.

What Are the Causes of High Nitrates?

  • A high fish stocking density

Excess stock is the most important factor in nitrate formation, which is the root of all causes. If you keep a lot of fish in the aquarium relative to the size of the tank, the formation of nitrates will be drastic!

  • Overfeeding

Overeating is a common cause of nitrate buildup and is easily controlled. Food leftovers eventually break down into ammonia and nitrates.

  • Accumulated plant matter

Aquarium plants are useful for nitrate control. But at the same time, dead leaves and crop stems can negatively impact nitrate concentration.

  • Accumulation of debris in the filter medium

Aquarium filters capture the finest biological waste and keep the water transparent. But the waste accumulated in the filter media can still be a source of nitrate formation as they are not visible but are present in the water.

How to Lower Nitrates in Freshwater Aquarium.

lower nitrate level

The essential elements of the nitrogen cycle in a freshwater aquarium are fish waste, uneaten fish food, decay of organic matter (leaves, etc.), live plants, bacteria, and nitrifying bacteria. The bacteria convert ammonia into nitrite and then into nitrate. Nitrite is considered one of the most toxic compounds to both plants and fish. Nitrates can also serve as food for plants because they provide nitrogen to the plants.

  1. Plant growth to reduce nitrate

Aquatic plants can absorb ammonia, nitrites, and nitrates. Therefore, converting your aquarium to a planted aquarium is the natural way to control nitrate concentration. Having live plants in the aquarium is a piquant idea. Not only do they de-nitrate, but they also beautify your aquarium beautifully.

  1. Changing water

The easiest way to control nitrate buildup is with regular water changes. At least, a weekly 10% to 20% of the water change must be performed. However, the replacement water must be nitrate-free and suitable for other parameters.

To lower the nitrate level in the aquarium in an abrupt manner, you can perform an initial 40% water change, add 40% of normal water then perform another 20% water change, after this, you can top up your water to the original 100% level of water, by this time, you would have a 10% level of the original substances in your aquarium water.

  1. Nitrate absorbing filters

If your aquarium suffers from strong nitrate deposits and changing the water is not enough, you can use special filters that bind nitrates. Anaerobic denitrifying biofilters are commercially available, which reduces the level of nitrate dissolved in the water.

  1. Regular replacement of the filter material

Replacing the filter material is routine maintenance that must be performed. It is very important to lower the dissolved nitrate level. Filter media trap waste to make the water clear, but this biological waste can be a source of nitrate formation.

  1. Low feeding

If the biological load of your fish is particularly high, reducing feeding is a good way to take control of the overall nitrogen cycle in the aquarium. Most aquarists overfeed anyway. A good rule of thumb for smaller fish is to remember that their stomach is roughly the size of their eyeballs.

In conclusion, high nitrates in your tank can pose a number of risks to your fish. If the high levels are not detected and treated, it can lead to diseases or other harmful conditions in fish. But with a few quick and easy steps, you can reduce nitrate levels in your tank, thereby keeping your fish healthy and alive.

Recommended Reading: Healthy Ways to Keep Fish Tank Clean Without Changing Water

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