Importance of Fertilisation
Similar to terrestrials plants, aquatic plants require nutrition for survival and thriving.
Macro-nutrients, used in large quantities (therefore the word 'macro'), are the main nutrients needed for healthy growth and refer to Nitrogen, Phosphorous, Potassium, Calcium & Magnesium, Sulfur. Together with carbon, these nutrients make up ~96% of plant mass.
Micro-nutrients, used in small quantities, refer to Iron, Chlorine, Boron, Manganese, Zinc, Copper and Molybdenum.
| Notable Element | Purpose |
| Nitrogen (N) | Major growth regulator |
| Phosphorous (P) | Plants cell generation and overall health |
| Potassium (K) | Activates basic enzymes for the production of food to produce healthy leaves |
| Iron (Fe) | Synthesis of Chlorophyll, Healthy Colouration |
| Magnesium (Mg) | Formation of Chlorophyll |
| Calcium (Ca) | Vital for cell division; the absorption and conversion of nitrate and for the carbohydrate metabolism of the plant |
Importance of CO2
For all plants, CO2 is crucial for survival; it is required in the process of photosynthesis, in which plants convert light, water, and CO2 to make sugar and oxygen. With 40-50% of plants' mass made of carbon, CO2 is an irreplaceble ingredient in maintaining a planted tank.
The optimal level of CO2 for plants is a stable concentration of 10-15ppm.
In natural environments which have thriving plant growth, there are organic decomposition and underground stores of CO2 that have 10-40+ ppm level of CO2. However, there is only 2-3ppm of dissolved CO2 in an aquarium tank because CO2 diffusion in water is 10000 times slower compared to in air. As such, injection of CO2 (gaseous or liquid form) in the planted aquarium has become a common practice amongst aquarists.
Injection of CO2 accelerates plant's growth rate by 5-10 times.
When optimally provided, CO2 enables plants to thrive in form, colour, density and health. On other hand, poor provision of CO2 causes plants to suffer from stunted growth, paling in the leaves and stems, and algae growth.
Having said that, there are some aquatic plants that can survive in a tank without CO2. These are what we called the low-tech plants that are sturdier and can survive in an environment of scarcity. Despite so, CO2 injection is necessary to bring out the deep coloration of some of these plants.
Importance of Lighting
Similar to CO2, light is another crucial element to plant's survival in the process of photosynthesis. There are three factors to consider to provide optimal lighting for a planted aquarium.
Firstly, the intensity of light, which is measured in 'μmols' of PAR (Photosynthetically Active Radiation). This unit of measurement indicates the amount of light available for photosynthesis. It is important to understand that 'lumens' and 'watts' are poor, or rather irrelevant, indicators for light strength. The former measures light brightness with respect to human eyes' sensitivity to the electromagnetic light spectrum, while the latter measures the electricity that is produced, instead of the output of light.
The general guideline followed by the aquarist community is...
| PAR (μmols) | Suitable for | Examples |
| 75-120 | Low light demanding plants | Most Anubias, Java Fern, Java Moss, Crypts, Amazon Sword, Vallisneria etc. |
| ~150 | Medium light demanding plants* | Rotala Blood Red,
Echinodorus etc.
|
| ~200 | High lighting demanding plants* | Ludwigia Super Red |
*These plants will survive under low lighting. However, to reveal their inherent bright redness, stronger lighting is required.
Secondly, spectrum of colours. To ensure better visual impact of coloured plants and most importantly, their colour pigmentation, red and blue lights are essential.
To be exact, red lights should take at least 50% of the spectrum, while blue lights shouldn’t exceed 15%. For photosynthesis, the most suitable wavelengths of visible light fall between the blue range (425–450 nm) and red range (600–700 nm). Also, stronger red/blue stimulates pigmentation in certain plants.
Thirdly, spread of light in the tank. The scape or setup of a tank has to have an even spread of light. A single light source wide bar fixture would usually result in poor distribution of light - a high value of PAR in certain areas (often the centre of the light) while the edges are shadowed. Therefore, experts would recommend two or more light sources on a distributed array fixture so that it covers most of the space.
Importance of Water
Relevant to the aquatic industry, measurements of pH, kH and gH are paramount to understand the condition of water in an aquarium.
pH measures the acidic level of water. Most fishes and plants prefer pH level between 6.4 to 7.8. That said, most livestock can easily adapt to a wide range but they cannot, however, live through large pH fluctuations (fluctuations of greater than 0.3 over a 24 hour period).
kH measures the concentration of carbonates and bicarbonates. It is also an indicator of buffering capacity of water, referring to the ability of the water to neutralise added acid without significantly changing the pH. A KH value lower than 4.5 dH necessitates monitoring the pH for swings.
gH measures the concentration of magnesium and calcium. Most plants are tolerant over a wide range of GH, and other for kH.
Most plants and livestocks do best in a range of 4-8 dH (degree hardness) or 50 ppm to 100 ppm, which would be considered somewhat soft.
For shrimps and snails, it is important to maintain approximately 4dH. Rather than a clear distinction between hard and soft water plants, it is more accurate to classify them across a spectrum of 'hardness tolerance'. That said, most plants that thrive in hard-water do fine in soft water, but not otherwise.
The sturdier plants species are Valisneria, Java fern, Anubias, certain Echin Swords and Cryptocorynes (mainly wendtii and lutea). Whereas the more sensitive species are Tonina, Syngonanthus, Blood vomit and Ammania etc.
Importance of Fertilisation
Similar to terrestrials plants, aquatic plants require nutrition for survival and thriving.
Macro-nutrients, used in large quantities (therefore the word 'macro'), are the main nutrients needed for healthy growth and refer to Nitrogen, Phosphorous, Potassium, Calcium & Magnesium, Sulfur. Together with carbon, these nutrients make up ~96% of plant mass.
Micro-nutrients, used in small quantities, refer to Iron, Chlorine, Boron, Manganese, Zinc, Copper and Molybdenum.
Nitrogen (N) is a major growth regulator.
Phosphorous (P) supports lants cell generation and overall health.
Potassium (K) activates basic enzymes for the production of food to produce healthy leaves.
Iron (Fe) is responsible for synthesis of Chlorophyll, healthy colouration.
Magnesium (Mg) supports formation of Chlorophyll.
Calcium(Ca) is vital for cell division; the absorption and conversion of nitrate and for the carbohydrate metabolism of the plant.
Importance of Filtration
A filter has four key purposes: 1) remove debris and ensure quality of water (mechanical filtration), 2) breed beneficial bacteria (biological filtration), 3) enable atmospheric oxygen to penetrate the tank and 4) provides water circulation within the tank.
The flow rate of the filter (or pump) has to be at least 10 times the volume of the tank. The more frequently the water circulates, the cleaner the water would be.
That said, the flow of the filter cannot be too strong as it might uproot the plants and create a whirlpool, endangering the other livestocks. An appropriate strength of current would circulate the CO2 and nutrients around the leaves and enable aquatic plants to take them up efficiently. This is especially important as CO2 and nutrients diffusion are extremely slow in water, and without circulation, it would tend to become limited locally around the leaves.