The Impact of Nutrients on Your Planted Aquarium

April 03, 2022 5 min read 0 Comments

Having a freshwater planted aquarium in your home is a wonderful way to stay connected with nature. During this time of pandemic and lockdown, there has never been a greater need or better time to try and bring a bit of nature into your home. Owning a planted aquarium is more than just building the environment; it is a long-term commitment to growing and maintaining your aquatic life. One of the most important parts of doing this is knowing how to provide the right nutrients to your aquatic plants. Let’s take a closer look at the nutritional requirements involved with having a freshwater planted aquarium in your home. 

Aquatic plants require very specific elements found in nature in order to develop and grow properly. Most of the nutrients, such as Carbon, Hydrogen, and Oxygen are derived from the air and water in your tank. These elements are the basis for physical plant structure and help to create carbohydrates, sugars, and starches to provide strength to the stems, leaves and cell walls of the plant. These elements are often referred to as “nutritive elements” and required by all plants.

Understanding the Nutrient Demands of Your Aquatic Plants

If you are new to the world of planted aquariums, it is important to understand the cycles of nutritional needs your plants will go through. When your plants are small and young, they will require lower doses of nutrients. As they age, your plants will eventually hit a state of vegetative growth and will require a significant increase of nutrients during this time. A stage of reproductive development follows and requires a much lower nutrient. This is a basic overview, but how you manage your nutrients during these early stages will greatly affect the overall development of your aquatic plants. 

The essential nutrients that your planted aquarium needs are found in two forms: macronutrients and micronutrients. Essentially, macronutrients are all the nutrients required most by the plant, whereas the micronutrients are the ones only needed in small quantities or not on a regular basis. Don’t be fooled by the name though, one nutrient is not more important than the other. Micronutrients are just as important as macronutrients as they are both essential for healthy aquatic plant growth.


Macronutrients are the elements needed in the greatest quantity in order to achieve healthy plant growth. They include Nitrogen (N), Phosphorus (P), and Potassium (K), commonly referred to as “NPK”. If your aquarium is densely planted, you will want to supplement NPK with your nutrient doses. If you don’t, you run the risk of starving your plants. This is also true if you plan to inject carbon dioxide, if you have several bright lights, or are growing medium-hard category plants.

Other macronutrients include Carbon (C), Oxygen (O), and Hydrogen (H). Carbon is not supplied through planted aquarium fertilizers and as a result, many tank owners choose to inject pressurized carbon dioxide into the environment. Also, on the list is Magnesium (Mg), Sulphur (S), and Calcium (Ca). Lucky for you, Oxygen, Hydrogen, Sulphur, and Calcium are normally found naturally in the tank water, so there is no need to supply them artificially. 

Like phosphorus, potassium is essential for strong plant growth. Unlike phosphorus, potassium isn’t created in large enough quantities from fish food and waste and thus requires a regular supplement in your dosing schedule.

You never want nitrite, and any non-zero amount of nitrate is ok assuming its under 40 or so.  Phosphorous is supplied by food and waste however in many tanks this is not sufficient for the plants needs and should be supplemented.


As mentioned above, just because they are called micronutrients doesn’t mean they are any less important than their macronutrient brother. These nutrients are simply needed in a much smaller quantity compared to the macronutrients. If your plants are deprived of the proper micronutrients, their growth will be stunted and they will look visually unappealing. It is quite easy to detect a micronutrient deficiency, as most plants will begin to show signs such as yellowing leaves, holes in the leaves, stunted growth, discoloration along the midvein, etc. 

The most important micronutrients are: Iron (Fe), Manganese (Mn), Chlorine (Cl), Copper (Cu), Boron (B), Molybdenum (Mo), Cobalt (Co), and Nickel (Ni). These micronutrients are usually found in your average complete aquarium fertilizers. If you plan to have a high fish load in your tank, you may need to find a micronutrient solution that is tailored to that type of environment. Not all solutions are made equal, but there is a solution that is right for your needs.

Types of Fertilizers

There is quite an array of fertilizers on the market and it can be overwhelming to know which is right for your planted tank. Most of the time you can get away with using a conventional “complete” fertilizer, especially if you have a decent fish-load in your tank. It is important to know that many fertilizers are lacking in phosphorus and/or nitrogen because manufacturers assume, they will be sourced from other parts of the tank. If you are noticing any deficiencies with your plants, consider adding these nutrients along with your complete fertilizer dose. 

There are two main types of fertilizers you will be working with in your planted tank:

Substrate Fertilizers: These fertilizers are used on the bottommost layer of your tank and are often mixed with your gravel (or whatever material you use) in powder form. Besides the powder form, substrates are available in tablet and stick form.

Water Column Fertilizers: These fertilizers are ideal for aquatic plants that do not have roots. These fertilizers will supply all the necessary nutrients and are suitable for daily or even weekly dosing. Regular (partial) water replacement is recommended with liquid fertilizers in order to prevent build-up in the tank.


Experienced aquarists know that dealing with algae growth in your tank is inevitable. Over time, the idea that cutting back on fertilizers would reduce or remove algae outbreaks has been passed around the community like a bad game of telephone. But not using fertilizer is actually more destructive to your tank because it promotes algae growth. By not providing your aquatic plants the nutrients they need, they begin to starve and wither, which are optimal conditions for an algae outbreak. The simple truth is that adding plant fertilizers will not cause algae growth.  

Changing the Water

Staying on top of your water’s nutrient levels is of the utmost importance. Partially changing out the water in your tank is recommended on a weekly basis. Replacing part of your water will help remove excess waste products and unnecessary nutrients from the environment. Changing the water regularly will help prevent algae outbreaks. Should you get an algae outbreak, carry out a 50% water change to remove pollutants from the water and clean any algae off your glass, plants, or fixtures.

Contact us if you have any questions about your aquarium plant fertilizer today.