How To Fertilize Aquarium Plants Naturally (Complete Guide)

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by Jason Matthews



Plants need fertilizer to grow and reproduce. Although it occurs naturally, there are various plant fertilization methods, even for aquarium plants.

Plants are a vital component of the aquarium ecosystem as they support the balance of oxygen and carbon dioxide. Aquarium plants also mimic natural hiding places and shelters for fish and other aquatic life in the wild.

This article reviews natural plant fertilization and how to do it properly to produce thriving and gorgeous plants in your aquarium.

Aquarium Plant Needs

Aquarium plants require basic houseplant needs – proper food, water, and light – though they differ in the specifics. Unlike houseplants, however, aquarium plants live and breathe the tank in the water. In other words, water is a major life source for your aquarium plants, fish, and other living organisms. Keep in mind that a couple of things could go wrong:

  • Imbalances in the water. Any change to your aquarium water can throw off its balance, whether it is pH, nitrates, or ammonia. Aquarium plants and fish are sensitive to any changes in the water, which could be fatal if done improperly.
  • Increase in algae. Drastically changing one chemical in the water could lead to algae growth. If not addressed immediately, algae growth could become uncontrollable and deprive your aquarium plants and fish.

As long as you do not treat aquarium plants like your average houseplant and take extra care fertilizing them, you can minimize potentially hazardous alterations to the aquarium water.

How to Naturally Fertilize Aquarium Plants

How to Naturally Fertilize Aquarium Plants

There are several synthetic plant fertilizers on the market. Most chemical fertilizers, especially those advertising complete fertilization care, tend to be more expensive due to their convenient one-step or few-step processes.

An effective biofilter and a little extra time dedicated to naturally fertilizing your aquarium plants will save you money.

Natural fertilizers are introduced in one of two ways: substrate or a water column. 

Fertilizing Through Substrate

By distributing the fertilizer directly into the substrate, the plant’s primary intake of nutrients will occur through the root system. This method is ideal for rooted plants. Floating plants like java moss or duckweed will not benefit from this.

Fertilizer Balls

For root-feeding plants, it’s best to insert fertilizer balls into the substrate. To create fertilizer balls, you will need: 

  • Five tablespoons of Calcium Montmorillonite Clay powder
  • One tablespoon of mixed powdered seaweed
  • Enough water to create a wet modeling clay consistency

First, combine the Calcium Montmorillonite Clay powder and mixed powdered seaweed in a bowl. Continue mixing and slowly add water until you achieve a wet modeling clay consistency. Once your mixture has the right consistency, form the mixture into balls and allow them to dry. After the balls completely dry, quickly insert them directly into the substrate. If not inserted quickly, the balls may dissolve in the water.

Fertilizer balls last an average of up to six weeks.

Fertilizing Through a Water Column

Aquariums with various plant types benefit most through water column fertilizer distribution. Water column fertilizers are put directly into the water and circulated throughout the tank. 

If you only have plants in your aquarium, they will intake the nutrients through their leaves and extremities. Nutrients that fall to the bottom of the tank can be taken in by the plant’s roots.

Fish Droppings and Fish Food

If fish live in your tank, fish droppings and excess fish food can fertilize your aquarium plants. Fish consume parts of the plant for their nourishment resulting in fish droppings that naturally fertilize plants. 

Any leftover fish food descends to the bottom of the tank or remains suspended in the water column. As time passes, the excess food continually breaks down into essential nutrients that feed and fertilize the plants.

Benefits of Natural Fertilization 

Benefits of Natural Fertilization 

Natural fertilization methods provide something synthetic or chemical fertilizers do not – sustainability. Once you have established a rhythm and understanding of what your aquarium plants need, the whole ecosystem will run its course. 

Natural fertilization is also an excellent way to display and teach the process of biofiltration. Introducing plants that help filter unwanted materials and chemicals from the water is an example of how ecosystems occur and thrive naturally.

Of course, continue to monitor to observe any changes or potentially harmful alterations to the aquarium’s environment. 

Why Not Synthetic Fertilizers?

Chemical or synthetic fertilizers won’t harm your aquatic creatures, but they tend to be costly and less intuitive. For those with busy schedules, chemical fertilizers may be worth the price if only for convenience.

Chemical fertilizers are also not as sustainable as natural methods because they come in large plastic bottles and containers. These chemicals are also processed heavily in factories and are less related to the natural sources of nutrients that the plants might experience in their natural habitats.

Related article: How to care for carpet plants

Natural Fertilization Successful Results

Properly fertilized aquariums will feature sturdy plants, clear water, and happy fish. The ecosystem of a healthy aquarium is a delicate balance between several nearly-competing factors that require the attention of the aquarium caretaker.

The natural fertilization methods for aquarium plants discussed above are just a couple of different solutions for those seeking a more sustainable, intuitive, and interactive aquarium setup. 

Remember that for natural fertilization aquariums, it is of the utmost importance to ensure that the tank has significant biofiltration. This will ensure that nutrients that are not helping the plants are not hurting them either.

How Often Should You Fertilize Your Aquarium Plants?

The upkeep of your fertilization methods depends on the size of your tanks and other factors such as plant type, whether or not your aquarium houses fish and other creatures, and the fertilization method. 

Some synthetic or chemical fertilizers will spell out each step, including a plant-feeding schedule. Generally, these fertilizers suggest a weekly schedule.

On the other hand, natural methods usually require more observation and research to determine what is best for the plants. Initially, check on your aquarium every few days and note any changes. You may not see any until two to four weeks after starting your natural fertilization process. From there, adjust your fertilization accordingly and continue closely monitoring your aquarium plants.


Jason Matthews

My name is Jason Matthews, and welcome to my website. When other kids were bragging about how their dog could sit and roll over, I was bragging about my latest Betta Fish and the cool sea castle I just added to his aquarium. 

Jason aquariume

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