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How to Add Nitrate to an Aquarium?

How to Add Nitrate to an Aquarium

Owning an aquarium and keeping it perfectly balanced can be a difficult task, so when something goes wrong it’s incredibly frustrating. One of the levels that has to constantly be monitored is the level of nitrates in the water.

Nitrates, which are the final product produced in the nitrogen cycle, aren’t good for fish in high concentrations, but the correct amount of nitrates is a sign that an aquarium is healthy. In a planted tank, nitrates are even necessary for plants to grow! If your nitrates are low, you might be wondering how to add nitrate to aquariums.

Add nitrate to your aquarium by adding potassium nitrate fertilizer, adding more fish, or waiting for the nitrogen cycle to stabilize. 

How to Add Nitrate to an Aquarium?

Most aquarium keepers would be thrilled to consistently have low nitrates in their tanks, but there are circumstances where adding more nitrates is necessary. 

Nitrates are 1 of the 3 substances most water testing kits monitor, the other two being nitrites and ammonia. Being able to test your tank is extremely important, because an imbalance of any of these things can have very detrimental effects on your fish. 

An aquarium with a healthy nitrogen cycle will have 0 ppm (parts per million) ammonia, 0 ppm nitrites, and a nitrate level below 50 ppm. 

Usually, you won’t have to worry about adding nitrates to your tank, because nitrates do nothing beneficial for fish or other tank livestock. Nitrates are created because of fish waste, so it’s easy to see why fish wouldn’t like too much of them in the water.

There is one circumstance where nitrates might be desired, though, and that’s in a planted tank. Plants do so well in aquariums because they are fertilized by the nitrates and fish waste. A planted tank with no nitrates will have little to no plant growth until nitrates are reintroduced. 

Here are some ways to add nitrates to your tank:

  • Adding potassium nitrate fertilizer: The simplest and most effective way to add nitrates is to simply add a fertilizer that contains them. Potassium nitrate fertilizers are made to feed aquatic plants.
  • Adding more fish: A lightly stocked planted tank may not produce enough waste to keep the nitrogen cycle going, leading to hungry plants. Adding more fish or other livestock to your tank can quickly raise nitrate levels, but don’t go overboard. More than 50 ppm of nitrates can harm fish. 
  • Waiting for the nitrogen cycle to complete: If your tank isn’t cycled, then there won’t be nitrates in the tank. Nitrates occur when ammonia and nitrites are broken down. This cycle is so important because fish  tolerate nitrates much better than ammonia or nitrites. A brand new tank will not have nitrates, so if you want to add plants, it’s necessary to do a fish-in cycle or a fishless cycle to get everything up and running

How Do You Fix Low Nitrate Levels in a Fish Tank?

Adding potassium nitrate fertilizer might give your tank more nitrates for the moment, but that is just a temporary solution. The best thing you can do to fix low nitrate levels in an aquarium permanently is to properly stock it with fish and other creatures, and make sure that the nitrogen cycle in the tank is established. 

The nitrogen cycle is one of the most important things in any aquarium by far. Without it, the ammonia from fish waste would just remain in the water, slowly poisoning the fish. A cycled tank will have nitrates, but not too many. So to completely fix low nitrate levels, the nitrogen cycle is imperative. 

What is the Nitrogen Cycle?

Understanding the nitrogen cycle in depth can seem like a daunting task, but when you break it down into simple steps it’s much easier to comprehend. 

The nitrogen cycle is basically a food chain of sorts. Here’s a short explanation of how it works:

  • Fish eat and make waste which is full of ammonia. 
  • This waste is eaten by a type of beneficial bacteria that transforms it into nitrites through their own waste.
  • Then this waste is eaten by a second type of beneficial bacteria. The waste from the second beneficial bacteria is nitrates. 
  • Plants and algae consume the nitrates 

Can Nitrates Be Too Low in an Aquarium?

If you don’t have plants in your tank, then your nitrates can’t be too low. Only planted tanks require nitrates. 

Fish don’t benefit from nitrates at all, so in a tank that has no real plants, the goal is to keep nitrates as low as possible. Planted tanks, on the other hand, requite nitrates for proper growth and plant health. 

Plants are basically nitrate sponges. This means that planted tanks aren’t just beautiful to look at, they also naturally have lower levels of nitrates, which fish are sure to appreciate. 

What Nitrate Level Is Safe for Fish?

As a rule, nitrate levels should be kept under 50 ppm for it to be considered safe for fish. Ideally, the nitrate level will be between 10-40 ppm. 

Fish can get sick from high nitrate levels, but not nearly as quickly or as severely as they can from high ammonia or nitrite levels. Still, we should avoid letting nitrate levels go over 50 ppm.

If your nitrate level is creeping up, it’s time for a water change. Never do a 100% water change, because this can crash your cycle altogether, so stick to water changes that replace 25-50% of the tank water instead. 

Final Thoughts 

  • Add nitrates to an aquarium by adding potassium nitrate fertilizer to the tank, adding more fish, or waiting for the nitrogen cycle to complete. 
  • Nitrates are necessary for plant health in planted tanks, but tanks without plants don’t require any nitrates at all. 
  • The nitrogen cycle will provide a constant supply of nitrates, because ammonia is broken down into nitrites, and nitrites are then broken down into nitrates. 
  • Nitrates are the final product of the nitrogen cycle, and at low levels, aren’t harmful to fish. If nitrates rise beyond 50 ppm, a water change is likely necessary. 

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