Is Nitrate Good or Bad for Your Aquarium?


Is Nitrate Good or Bad for Your Aquarium?

If you search online for information about nitrate in fish tanks, many articles immediately pop up to warn you about the dangers of high nitrate and the best methods for lowering it. But how much nitrate is considered dangerous? What if nitrate is so dangerous, then why are many aquarium fertilizers increasing nitrate levels? Let’s talk about one of the main points of confusion in the aquarium hobby – nitrate.


What is Nitrate?

Fish and other animals waste toxic nitrogen compounds such as ammonia when they eat and poo in an aquarium. The fish tank’s beneficial bacteria naturally grows and consumes ammonia. This purifies the water and makes it safe for fish to drink. However, one of the end products generated by the beneficial bacteria is


. While nitrate is much less toxic than ammonia it can also cause harm to animals in large quantities. The Easy Guide to the Nitrogen Cycle in Aquariums has more information.

How to Measure Nitrate

Because nitrate is colorless and odorless it cannot be seen by the naked eye. Therefore, fishkeepers use water test strips to measure it. Aquarium Co-Op Multi-Test Strips, for example, measure nitrate along with five other parameters in less than a minute. Simply dip a test strip in the aquarium water, such that all the test pads are submerged, and gently swirl it underwater for 3 seconds. You can then remove the test strip from the aquarium water without shaking it off. Keep it horizontal for 60 seconds. Compare the test results immediately with the color chart provided to see the amount of nitrate.

Use multi-test strips for measuring nitrate and other water parameters.

What are safe levels of nitrate in aquariums?

Some nitrogen waste compounds, such as ammonia or nitrite, can be toxic to animals in trace amounts. However, nitrate is much less toxic. However, little research has been done to determine how toxic nitrate is to all of the different animals we can keep in our aquariums. To give you an idea of the situation, a paper on Nitrate toxicity to aquatic animals reported that nitrate concentrations rose to 800 ppm just before becoming fatal to guppy eggs. We personally recommend keeping less than 80-100 ppm nitrate in your fish tanks.

Many people see this upper limit for nitrate and assume that, for the health of their aquarium animals, it would be best to lower nitrate as much as possible. Although fish, shrimp, and snails are not affected by a lack of nitrate in their aquariums, they do need it for good growth. The nitrate levels drop to 0-20ppm and leaves turn yellow or translucent, especially at the tips. They then have to use nutrients from their old leaves at bottom to make new leaves. In our tanks, we aim for 50 ppm nitrate.

Signs of nitrogen deficiency

How to Lower Nitrate in High Bioload Tanks

Fish tanks that are overstocked with fish or have few aquarium plants can lead to a naturally high level of nitrates. You can reduce nitrate levels quickly and easily by performing a partial waterchange. You can remove 30- to 50% of the old, nitrate laden water with an aquarium siphon. Then, you can refill the tank again with fresh, clean water. We don’t want to shock the fish with huge water changes. If your nitrate level exceeds 100 ppm, multiple water changes may be necessary over several days. This flow chart will show you how to make water changes.

We know that most people don’t like water changes so let’s explore some ways to keep nitrate levels low. Aquariums that have high bioload often have high levels of nitrate. This is because there are lots of fish poop, leftover food and other rotting materials in the water. To reduce nitrate long-term, you can decrease the number of fish and/or the amount of food in your tank. If you don’t want to reduce your fish population, consider upgrading the aquarium or adding large numbers of live plants. Aquatic plants are a great choice because they consume nitrate naturally, which allows them to grow more roots and leaves. Pogostemon and water sprite are faster than slower-growing plants like anubias or java fern at eliminating nitrate.

Is fish poop enough fertilizer for aquarium plants?

Besides light and water, plants require an exact mix of nutrients to give them the fundamental building blocks needed to survive and thrive.


are nutrients that plants consume in significant quantities (such as nitrogen, phosphorous, and potassium), whereas


are nutrients that plants need in trace amounts (such as iron, boron, and manganese). Traditional wisdom believed that fish poop and uncooked fish food provided sufficient nutrients for plants to grow. But, in reality, these nutrients are not in the proper amounts or ratios. When beginners try to keep plants without any fertilizer, the plants often develop serious nutrient deficiencies within a few months. Easy Green was created to address this problem. It is an all-in-one fertilizer that helps keep plants healthy.

As you can see in the list of nutrients above, the purpose of Easy Green is to raise nitrate (or nitrogen) and other nutrients so that plants have enough to consume. Because they are macronutrients, your plants require more of them, the percentages for nitrate and phosphate are higher than others. Easy Green will cause an increase in nitrate if added to water. This can be measured using a test strip or kit. The goal is to add enough Easy Green to reach 50 ppm.

How to keep the right amount of Nitrate in Aquatic Plants

How do we reach the ideal concentration of nitrate without having too much or too little? You can see that your aquarium is consistently producing nitrate.

Too much nitrate

You may feel tempted to stop using Easy Green as it will increase nitrate levels. However, withholding fertilizer may end up depriving the plants of other essential nutrients besides nitrate. The following guidelines will help you prevent this from happening:

1. Perform a 50% water changing (or multiple 50% water changing every four days) until the nitrate level reaches 25ppm. 2. One pump of Easy Green for every 10 gallons water. Give the water a rest for a few hours before testing it again. 3. You want to get to 50 ppm nitrate. If nitrate is still too low, repeat Step 2 to keep dosing fertilizer until you reach 50 ppm. 4. Then wait 3-4 days before testing the water again. A 50% water change will be required if the nitrate levels are already between 75 and 100 ppm. To reduce the amount of nitrate that is building up, you can remove fish and add more plants (especially fast-growing ones).

Quick dosing using Easy Green all-in one fertilizer

However, if your plant tank has to little nitrate you need to fertilize regularly to prevent starvation. As a starting point, we recommend dosing 1 pump of Easy Green per 10 gallons of water with the following frequency:

Low light aquariums require to be administered once each week. Medium light aquariums require twice each week.

A customized dosing system may be required if you notice that the leaves of your plants are still developing holes and melting. This is based on the water’s nitrate levels.

Record down the dates you fertilized the tank and the amounts of Easy Green used, and soon you should be able to figure out your custom dosing schedule. If you have trouble doseing enough fertilizer, decrease the lighting or CO2 injection. Then repeat the previous steps. Also, be aware that as plants and fish grow bigger or are removed from the aquarium, this changes the amount of nitrate that is needed, so keep an eye on the growth of the plants and test your water to adjust the schedule as needed.

Bottom line: do not be alarmed if you see nitrate readings higher than 0 ppm. Nitrate can be good for plants. Easy Green is a beginner-friendly fertilizer that you can use without measuring out many supplements. Just add 1 pump per 10 gallons and watch your plants grow.