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. What is the safe limit for nitrate? 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?

When fish and other animals eat food and poop in the aquarium, their waste produces toxic nitrogen compounds like ammonia. Beneficial bacteria in the fish tank naturally grows and consumes the ammonia, purifying the water in the process and making it safe for fish to live in. One of the products that the beneficial bacteria produces is however


. Nitrate is significantly less toxic than ammonia, but in large amounts, it can also start to negatively impact animals. The Easy Guide to the Nitrogen Cycle For Aquariums provides more information.

How to Measure Nitrate

Since nitrate can’t be seen with the naked eye, it is neither colorless nor odorless. Fishkeepers typically measure it using water test strips or chemically reacting kits. For example, Aquarium Co-Op Multi-Test Strips quickly measure nitrate and five other parameters in just a minute. Just dip the test strip in the aquarium water until all test pads are covered. Then, gently swirl the strip underwater for 3 seconds. After dipping the test strip in the aquarium water, shake off any excess water. Then keep the strip horizontally 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?

While some nitrogen waste compounds like ammonia and nitrite are toxic to animals at even trace amounts, nitrate is considerably less toxic. It is not known how toxic nitrate really is for all species of animals that can be kept in aquariums. A research paper entitled Nitrate toxicity to aquatic animals states that nitrate levels reached 800ppm in order to make them lethal for guppy fry. We recommend keeping fish tanks below 80-100 ppm of nitrate.

Many people view this as the maximum level of nitrate, and believe that it is best to reduce it as much possible for their aquarium animals’ health. Live aquarium plants need nitrate to thrive. Fish, shrimp, and snails do not suffer from a lack of it. Plant leaves can become translucent or yellowish if the nitrate level drops below 0-20ppm. This is because the plant has to consume nutrients from the bottom to grow new leaves. In our tanks, we aim for 50 ppm nitrate.

Signs of nitrogen deficiency

How to Lower Nitrate In High Bioload Tanks

If you have a fish tank that is heavily stocked with animals or does not have a lot of aquarium plants, the nitrate level produced by fish waste can naturally climb to 80-100 ppm and above. The fastest, short-term way to lower nitrates is to physically remove it from the aquarium by doing a partial water change. 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. Generally speaking, we want to avoid shocking the fish by doing huge water changes, so if your nitrate level is far greater than 100 ppm, you may need to do multiple water changes over the course of several days to safely lower the nitrate. Our flow chart for water modifications provides a step-by guide.

Most people don’t like frequent water changes. Let’s examine some methods to maintain lower nitrate levels. 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. The best ways to reduce nitrate over the long-term are to decrease the amount of fish and/or food that is put into the tank. If you are not interested in reducing the fish population, you can upgrade your aquarium or add large amounts of live plants. We love aquatic plants as they naturally consume nitrogen, which allows them grow more leaves and roots. Pogostemon.stellatus and water sprite, which are fast-growing, can eliminate nitrate faster than slow-growing plants like anubias.

Is Fish Poop a Good 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.


These are nutrients that plants need in large quantities (e.g., nitrogen, phosphorous and potassium).


These nutrients are essential for plants and can be found in trace quantities (such as iron boron and manganese). It was believed that fish poop or uneaten fish foods were enough nutrients to support plant growth. However, in reality they don’t contain all the necessary nutrients in the correct amounts. Plants that are kept by beginners without fertilizer often suffer from serious nutritional deficiencies in a matter of months. Easy Green was created to address this problem. It is an all-in-one fertilizer that helps keep plants healthy.

Easy Green has the goal of increasing nitrate and other nutrients to ensure that your plants have enough nutrients. Because they are macronutrients, your plants require more of them, the percentages for nitrate and phosphate are higher than others. Easy Green can increase the nitrate level when tested with a water test strip. It is important to use enough Easy Green to achieve a nitrate level of 50 ppm.

How to keep the right amount of Nitrate in Aquatic Plants

How can we achieve the perfect concentration of nitrate in our aquariums without having too little or too much? Your planted aquarium should have a consistent amount of nitrate.

Too much nitrate

, you may be tempted to stop using Easy Green since it will further 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. Your goal is to achieve 50 ppm of nitrate. If the nitrate remains too low, continue with Step 2 until it reaches 50ppm. 4. Wait 3-4 days and test the water again. You will need to change 50% of the water if the nitrate level is higher than 75-100ppm. 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

On the other hand, if your planted tank always has too little nitrate, you should regularly dose fertilizer to avoid starving your plants. For 10 gallons of water, you should use one pump of Easy Green.

– Dose once a week for low light aquariums. Medium light aquariums require twice each week.

If you find that your plant leaves are still developing holes and melting away, a customized dosing method may be needed, based on the nitrate level of the water.

You should keep track of the fertilizer used and the dates that you fertilized the tank. Soon you will be able figure out your personal 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.

Don’t worry if you see nitrate levels higher than 0ppm. Nitrate can be good for plants. Easy Green was created to be a beginner-friendly fertilizer. Simply add 1 pump for every 10 gallons to your plants and watch them grow.