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 …

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? And if nitrate is so toxic, why do many aquarium plant fertilizers increase nitrate levels when they are made to be safe for fish, shrimp, and snails? 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. One of the products that the beneficial bacteria produces is however


. Although nitrate is less toxic than ammonia in small amounts, it can still cause serious health problems for animals. For more information, read The Easy Guide to the Nitrogen Cycle for Aquariums.

How to Measure Nitrate

Nitrate cannot be detected by the naked eye since it is both colorless and odorless, so fishkeepers usually measure it using either water test strips or kits that chemically react to the nitrate in the water. Aquarium Co-Op Multi-Test Strips measure nitrate quickly and five other parameters in under 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. You can then remove the test strip from the aquarium water without shaking it off. Keep it horizontal for 60 seconds. As soon as the time is up, immediately compare the results with the included color chart to read the nitrate amount.

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

What are the Safe Levels of Nitrate for Aquariums?

Some nitrogen waste compounds, such as ammonia or nitrite, can be toxic to animals in trace amounts. However, nitrate is much less toxic. It is not known how toxic nitrate really is for all species of animals that can be kept in 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 recommend that fish tanks contain less than 80-100ppm nitrate.

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. When nitrate drops to 0-20 ppm, plant leaves can turn yellow or translucent (especially starting at the leaf tips) and eventually melt away because the plant is forced to consume nutrients from its old leaves at the bottom in order to make new leaves at the top. We aim to maintain a minimum of 50 ppm of nitrate in our planted tanks.

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. Take out 30-50% of the old, nitrate-laden water using an aquarium siphon and refill the tank with fresh, clean water. In general, it is best to not shock fish with large water changes. For example, if the nitrate content in your tank is greater than 100ppm, then you will need to make multiple water changes over several days. Our flow chart for water modifications provides a step-by guide.

Since most people don’t enjoy doing frequent water changes, let’s look at some approaches for keeping nitrate levels lower in the first place. Aquariums with high bioload are more likely to have high levels of nitrate. This means that there is a lot of fish waste, leaves and other rotting organics in the water. Hence, the easiest methods to reduce nitrate in the long term include decreasing the number of fish and/or amount of food that goes into the tank. If you don’t want to reduce your fish population, consider upgrading the aquarium or adding large numbers of live plants. We love aquatic plants as they naturally consume nitrogen, which allows them grow more leaves and roots. In general, fast-growing plants like water sprite and Pogostemon stellatus are capable of eliminating nitrate at a quicker rate than slow-growing plants like anubias and java fern.

Is Fish Poop a Good Enough Fertilizer for Aquarium Plants?

Plants need more than light and water. They also require the right nutrients to provide them with the essential building blocks they need to thrive.


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


There are trace amounts of nutrients that plants require, such as iron, manganese, and boron. 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. If beginners attempt to grow plants without fertilizer, they often experience serious nutritional deficiencies within a matter months. To address this common problem, we developed Easy Green as an easy, all-in-one fertilizer to help keep plants healthy and well-fed.

Easy Green’s purpose is to increase nitrate (or nitrous oxide) so that plants can eat enough. The percentages of potassium, phosphate and nitrate are actually higher than the rest, because these macronutrients are more important for plants. As a result, adding Easy Green will increase nitrate when measured by a water test strip or kit. In fact, the goal is to dose enough Easy Green until the nitrate level reaches 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? Your planted aquarium should have a consistent amount of nitrate.

Too much nitrate

You may feel tempted to stop using Easy Green as it will increase nitrate levels. You could end up denying plants other vital nutrients than nitrate by withholding fertilizer. The following guidelines will help you prevent this from happening:

1. Do a 50% water change if nitrate levels are 50 ppm or higher. Repeat this four times per day until the nitrate drops to 25 ppm. 2. One pump of Easy Green for every 10 gallons water. Wait a few hours and test the water again. 3. Your goal is to achieve 50 ppm of nitrate. If nitrate is still too low, repeat Step 2 to keep dosing fertilizer until you reach 50 ppm. 4. Wait 3-4 days and test 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 with 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:

For low light aquariums, you should do once per week. Medium light aquariums require twice each week.

You may need to adjust the amount of nitrate in the water if your plant leaves continue to develop holes or melt away.

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.

The bottom line is don’t be alarmed if your nitrate readings are higher than 0. Nitrate is good and even necessary for plants. Easy Green was created to be a beginner-friendly fertilizer. Add 1 pump to 10 gallons of water and watch your plants grow.