Introduction to the planted aquarium

Introduction to the planted aquarium

In the wild, these plants play an important role in removing nutrients from rivers and streams, as well as providing nice hiding places for fish and fry.

It makes sense that we use these benefits, by growing aquatic plants to create aesthetically pleasing aquariums, while also improving water quality (leading to a visible reduction in algae) and providing our fish with a natural, healthy environment.

There are four main elements that aquatic plants need to thrive: water, light, nutrients, and carbon dioxide.


All plants need water to live, and obviously this is especially important for aquatic vegetation. While most aquatic plants grow completely submerged underwater, there are some species that will also grow emerged as long as their roots are submerged.

Leaf shape can differ depending on whether the plant is growing in water or on the surface. There are also bog plants that can be grown in paludarium -style mounts, which will flourish if only their roots are kept moist.

Most aquatic plants will do well in most types of water, as long as extremes of pH and hardness are avoided, although there are a number of species that will require specific parameters. If you want to know more, you can take a look at our guide to aquarium plants for beginners.

Light in the planted aquarium

Plants make their own food to grow through a process called photosynthesis. The chlorophyll in leaves uses energy from sunlight to produce glucose from water and carbon dioxide, and also produces oxygen as a byproduct.

To grow properly, aquatic plants require full-spectrum aquarium lighting that replicates natural daylight. Some plants will require more or less light than others, but most plants need 8-10 hours of light per day.

While there are a small selection of plants that thrive in low to moderate light conditions (the type of lighting that comes standard in many aquarium kits), you’ll need to upgrade your lighting if you want to keep a wider range of species, including many of the attractive groundcover plants in the foreground.

Depending on the budget, high output T5 fluorescent bulbs (which can be further enhanced by the use of reflectors), metal halides or the latest energy efficient planted aquarium led display systems are suitable for growing your aquatic plants.

Stronger lighting will help encourage red pigmentation in many stem plants, although it should be noted that with increased light levels it is important to maintain optimal carbon dioxide levels.

plant nutrients

Aquatic plants require various nutrients to thrive. Macronutrients are nutrients that plants need to consume in large amounts, such as nitrogen, phosphorus, and potassium. Micronutrients such as iron, magnesium, and manganese are required in much smaller amounts, but are important for plant growth and health.

Although tap water contains a number of nutrients and minerals, many of them are used up quickly or are present at levels too low to be considered of much use to plants.

Some macronutrients will come from fish waste once it is broken down by filter bacteria, but this will not be enough to support the plants and they will need to be supplied with quality fertilizers (containing both macro and micronutrients) on a regular basis.

Liquid additives are convenient and easy to use, and can be added right after a partial water change. In addition, the choice of substrate can make a difference.

the substrate

Many aquarium substrates are quite large (greater than 4mm) and allow water to pass through easily; Unfortunately, however, water flowing through the growing medium can also remove a lot of useful nutrients from plant roots.

A finer grade substrate (1-2mm), such as silica aquarium sand, will allow a moderate amount of water movement, preventing the substrate from becoming stagnant, but reducing the amount of nutrients lost. To further enhance the substrate, a nutrient-rich, porous planting medium can be mixed into the lower layers for plant roots to find.

Some modern planting media can also be used on their own as a stand-alone substrate, providing both nutritional value and an attractive base to complement your plants.

Alternatively, if it’s too late to change your choice of growing medium, there are plant fertilizer tablets available that can be pushed down into the growing medium near the plant roots as needed.

Carbon dioxide (CO2)

Carbon dioxide is essential for the growth of aquatic plants. Without it, the light and nutrients in the water cannot be used for photosynthesis.

There will already be small amounts of CO2 in the aquarium, as it is a by-product of fish respiration and gas exchange at the water surface; however, for aquariums with a larger number of plants, this CO2 will be used up quickly and there will not be enough space available for all the plants to photosynthesize and grow.

Low CO2 levels in the presence of strong lighting and good nutrient levels can also lead to nuisance algae, so getting the balance right is important. You can increase the amount of CO2 in your aquarium by using a CO2 injection system.

Starter kits, like simple fertilizing pots, offer an inexpensive option for beginners. However, pressurized systems provide more precise control over the amount of CO2 that is released and allow the CO2 to be turned off at night using a magnetic solenoid valve. During the hours of darkness, it is not necessary to supplement with CO2 since the absorption of the plants is greatly reduced.

Using a plug-in timer in conjunction with the solenoid valve will provide a fully automated system. A word of warning though: CO2 can be toxic to fish. Levels should always be kept below 30ppm (test kits are available), so be very diligent not to add too much.

Keep in mind that some species are more susceptible to poisoning than others, particularly those found in oxygen-rich environments like hillside streams and rapids, so do some research and choose fish that are appropriate for this type of environment. CO2 fertilization has quite revolutionized the hobby of planted aquariums.

With the addition of CO2, cultivating the amazing lush waterscapes we see in books/magazines and on social media can now become a reality for everyone. If you are interested in these spectacular aquariums, you may be interested in our guide to aquascaping for beginners.

Aside from the problems that riverine fish will have with CO2 injected tanks as mentioned above, there are other considerations to keep in mind when selecting fish for the planted aquarium. Many common fish such as barbels and larger gouramis are voracious plant eaters, and others, including many cichlids, can burrow into the substrate and uproot plants.

Ideal species might include small, peaceful fish such as tetras, rasboras, and rainbow fish, along with dwarf catfish (otocinclus spp.) and nerita snails to control algae without harming plants.

While the lusciously colored dwarf shrimp (caridina and Neocardina spp.) have become very popular for nano tanks, they are not suitable for tanks with CO2 injection. However, they are ideal residents for the low-tech planted aquarium where CO2 is not used.

Acuario3web is happy to help plant enthusiasts and recommend a wide range of products online, including lighting systems, substrates, fertilizers, CO2 kits and test kits, with many more products available on the market. Please note that some stores also offer a CO2 refill service.

If you are still interested in setting up your own aquarium with live plants, we have a more extensive guide on how to make a planted aquarium that you will surely like.

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