Growing and maintaining a freshwater planted aquarium is not a difficult task, thanks to the technology and access to information that has made it easier to keep fish and plants healthy. To replicate a natural environment in your aquarium, live plants are essential. Besides looking nice, they promote a balanced ecosystem and provide many benefits, such as producing oxygen and consuming CO2, preventing algae growth, and keeping your fish healthy by providing them with an engaging environment.

To maximize your success and enjoyment with your aquarium, it's important to understand the basic needs of aquatic plants. Aquarium plants need clean, moderately soft water, full-spectrum light, nutrients, and a suitable substrate.

Water Requirements

Most aquarium plants do best at a pH between 6.5 and 7.8, with a general hardness of 2° to 6° dGH (50 ppm - 100 ppm) and alkalinity between 0° and 3° dKH (0ppm – 54 ppm).

(Note: While a General Hardness of  2° to 6° dGH produces the best growth in plants, Shrimp and Snails do better when there is calcium present in the water, so having 5° to 8° dGH (90 ppm - 140ppm) is typically a better range for most aquariums.
Higher KH levels may be required if you aren't running Co2 Injection. This is because, without Co2 injection, the plants will go looking for carbon in your KH and will consume it instead of gaseous carbon.)

Nitrate levels should be below 10 ppm and phosphates below 0.5 ppm to prevent algae from growing on leaves. Temperature should be between 24° and 26° C, and changing 10% of the water weekly or 25% bi-weekly and using Reef Carbon or an Organic Adsorption Resin in your filter to remove organic pollutants is also essential.

Proper circulation is important for plants, as it ensures a steady supply of nutrients, inhibits algae growth, and prevents the accumulation of organic debris on leaves.

Aquarium plants are sensitive to changes in water quality. Make sure to test your water regularly and make adjustments as needed to keep the water quality within the recommended parameters.

Lighting

Choosing the right light for a planted aquarium depends on the species you want to grow and the height of your aquarium. Some plant species need more intense light to thrive, and because light does not penetrate water very well, a stronger light source is needed for taller aquariums.

Aquatic plants do best under full spectrum light with a Kelvin rating between 6,500K and 8,000K, and you should always choose a light source specifically designed for growing aquarium plants.
Lumens, PAR (photosynthetically active radiation), and PUR (photosynthetically usable radiation) are more meaningful measurements than "watts per gallon.

Aquatic plants do best with 10 to 12 hours of light per day. Leaving the light on longer will not compensate for weak lighting, and it's important to create a consistent day/night cycle. Replace high output T5 and other fluorescent bulbs every 12 months to get the best light output. Finally, keep glass covers clean to allow maximum light penetration.

Excessive lighting can cause unwanted algae growth, especially if Nitrate and Phosphate levels are higher than recommended. If you are having issues with algae growth, you can reduce lighting down to 8 hours per day. If problems persist, you can run as little as 6 hours of light per day.

Substrate

Choosing the right substrate ensures proper root development and anchoring of rooted plants. Fine to medium grade gravel or coarse sand are best, and you can also mix different grades for texture and aesthetics. Avoid ultra-fine sand and coarse gravel, as fine sand compacts and doesn’t "breathe," while coarse gravel inhibits proper root anchoring and may collect excessive amounts of organic debris.

The preferred substrate for aquatic plants is a clay-based soil, which balances pH and provides a nutrient-rich environment that feeds the plant roots.

Fertilising

Aquatic plants require a constant supply of nutrients to grow well. Fertilize your plants regularly. You can use liquid fertilizer or root tabs to provide your plants with the nutrients they need.

Macro-Nutrients

Plants require nutrients in varying amounts, and macro-nutrients are those needed in the largest quantities. These include:

• Nitrogen
• Phosphate
• Potassium
• Calcium
• Magnesium
• Sulfur.

Macro-nutrients and carbon together make up almost all of a plant's mass, with carbon being the most significant component. While air and water provide the basic building blocks of hydrogen and oxygen, the other essential elements come from soil or water depending on the type of plant.

Although carbon comprises 45% of a plant's dry mass, naturally occurring dissolved carbon in tap water is typically low. Plants use carbon 10 times more than all other macro-nutrients combined, making CO2 injection a critical factor in plant growth. Without CO2 injection, tank CO2 levels are typically around 2-3ppm, but they can be increased to 40+ppm with CO2 injection.

This increased CO2 level results in growth rates in injected tanks that are 5-10 times higher than in non-injected tanks. Additionally, the nutrient requirements of a CO2-injected tank also increase proportionally.

To feed plants that take nutrients through their roots, use special aquatic plant substrates that contain embedded nutrients or insert fertilizer tablets into the substrate near plant roots. Do not use plant tabs or fertilizer sticks intended for houseplants, as they may not have the correct balance of nutrients for aquatic plants.

Micro-Nutrients

As their name suggests, micro-nutrients are required by plants in very small quantities. The scale of these micro-amounts can be hard to grasp. For instance, plants utilize 100 times more potassium than iron. The following are the essential micro-nutrients required by plants:

• Iron
• Chlorine
• Boron
• Manganese
• Zinc
• Copper
• Molybdenum

Lieberg's Law

Liebig's law of the minimum states that plant growth is limited by the availability of the scarcest resource. This means that providing an abundance of other nutrients will not enhance growth if another crucial factor is not equally increased. Hence, the significance of using a comprehensive fertilizer cannot be overstated.

A typical plant dry mass composition is shown in the table below:

Nitrogen (Ammonia NH3, Nitrates NO3):

Aside from Carbon, nitrogen is the element that plants utilize the most and is a major growth regulator. In nature, nitrogen is often a limiting factor, and plants rapidly utilize new sources of it. Altering nitrogen levels in an aquarium can speed up or slow down growth rates. Some aquatic plant species, such as Rotala rotundifolia, Ludwigia arcuata/brevipes, and Limnophila aromatica, display redder coloration when nitrogen levels are low due to the delayed development of chlorophyll. It is recommended to maintain stable nitrogen dosing in the tank to prevent plants from constantly resetting their growth rates, which can lead to several issues. In a well-stocked tank, livestock waste can contribute a significant amount of nitrogen.

Phosphorus (Phosphates, PO4):

In the absence of phosphate, colored plants tend to lose their intensity and become paler. Tanks that house a considerable amount of livestock usually have an adequate supply of phosphate.

Potassium (K):

Potassium is essential for various vital plant functions. Planted tanks in areas with tap water lacking in potassium tend to encounter several issues quickly if there is insufficient K levels. Commercial fertilizers usually contain potassium, but it may not be in the optimal amount. Livestock waste does not provide potassium optimally.

Iron (Iron chelates, soils, Fe):

Unlike NPK, iron is an immobile nutrient, and plants cannot transfer it from old leaves to new growth. As a result, a deficiency in iron is typically first noticeable in the yellowing of new leaves and poor coloration in colored plants. Contrary to popular belief among hobbyists, providing excess iron does not stimulate additional pigmentation in red plants. It is more crucial to maintain regular dosing to keep iron at an adequate level.

Magnesium (Mg):

Magnesium is a crucial component of chlorophyll. While it is commonly found in tap water, in areas where it is absent, regular dosing is essential. Unfortunately, many commercial fertilizers fail to include this vital element in their formulations.

Trace elements (Boron B, Copper Cu,...etc):

Although plants require trace elements in minute quantities, they play a crucial role in determining plant colouration and growth form. In high-speed CO2 injected tanks, it's common to have sub-optimal levels of trace elements due to the rapid growth rate. Even though the required dosage of trace elements is very low, it is important to administer it regularly.

Chlorophyll chemical structure.

Relying on Livestock Waste?

Planted tanks lack the natural nutrient cycle found in truly natural environments where organic decomposition and mineral erosion replenish nutrients in the soil. Although aquarium soil substrates can provide nutrients for a while, they eventually deplete. Water changes remove soluble nutrients and the tap water used may or may not replenish them. Depending solely on fish waste is insufficient, as fish do not produce certain nutrients such as chelated iron as waste. Livestock waste from fish-heavy tanks may contribute significant amounts of nitrates and phosphates, but other essential elements like iron, trace elements, and potassium are often insufficient. High levels of organic waste can trigger algae blooms and the "no dosing" approach may suffice for some tanks, but it does not promote optimal growth.

Deficiencies

In general, when plants lack the necessary nutrients, their growth rate decreases. Rooted species may direct their energy towards root growth to search for nutrients in the substrate layer. Depending on which nutrient is deficient, various symptoms may appear, such as paler leaves or whitish shoots, thin stems, and smaller leaves. Mobile nutrients like NPK and Mg can be scavenged from old leaves and redirected towards new growth, resulting in premature shedding or yellowing of older leaves.

Weak and unhealthy plants are the main cause of algae, making it crucial to feed plants regularly to maintain their health and prevent algae growth.

Deficiency charts may not always be accurate, and inexperienced hobbyists should be cautious about drawing hasty conclusions that all plant health issues stem from nutrient deficiencies. Non-nutrient-related factors may also be at play.

Dosing only when deficiencies are apparent is not a reliable approach, as the plant may already be stunted, and problems like algae may have already arisen. A better method is to establish a regular dosing routine for all required elements to prevent deficiencies in general. This can easily be accomplished with a wide-spectrum liquid fertilizer, which is the default approach in most successful planted tanks.

Choosing appropriate plants

To select appropriate plants for your aquarium, factors such as lighting, tank height, desired visual outcome, and fish species must be considered. Seek guidance from an aquarium expert or conduct research to choose the most suitable plants.

When arranging your plants, position tall or fast-growing species towards the back, visually striking plants in the middle, and shorter varieties at the front. Some foreground plants have lateral growth, so ensure there is enough space for them to spread out. Avoid planting shorter plants near broadleaf species that may obstruct light access.

Types of Aquarium Plants

There are many different types of aquarium plants available. Some of the most popular types include:

• Low-light plants:  These plants can grow in low-light conditions. Some examples of low-light plants include Anubias, Java Fern, and Java Moss.
• Medium-light plants:  These plants need moderate light to grow. Some examples of medium-light plants include Amazon Swords, Milfoil, and Water Wisteria.
• High-light plants:  These plants need bright light to grow. Some examples of high-light plants include Red Root Floaters, Rotala H'ra, and Ludwigia Dark Orange.

If you notice that your plants are not doing well, it is important to troubleshoot the problem early. Some common problems with aquarium plants include:

• Not enough light
• Not enough nutrients
• Poor water quality
• Pests or diseases