Excellent plant growth lies in the substrate. If you don’t have a suitable and balanced substrate your plants will not thrive the way you would like them to.
The substrate not only has a providing, but also a retaining capacity to hold nutrients for the use of plants over a period of time.
Nitrogen, calcium, potassium, and phosphorus are in ample supply in the aquarium, and also sufficiently available in tap water.
Other nutrients and trace elements such as iron, zinc, copper, etc. are present in the substrate and need to be added from time to time to ensure proper plant growth.
It is well established, that plants are able to take up nutrients through their leaves and root system. The only nutrients necessary in the water are calcium, magnesium, potassium (limited), and carbon. The other essential nutrients should be in the substrate, as the substrate and the plants have the ability to store those nutrients for a period of time, making them available when needed. It is recommended to have phosphates available in the substrate rather then the water column.
If you’re asking why nitrogen is not mentioned to be in the water for plants to take up, it’s quite simple: Plants can more easily take on nitrogen under anoxic (oxygen free area) conditions, which the substrate provides for. This also affects iron and potassium.
For the overall quality and health of your aquatic environment as well as healthy, thriving plants, nitrogen among others should not exceed certain levels in order to maintain an overall helthy aquatic environment. This will simplify maintaining your tank and avoid the need for painstaking steps and corrective measures required to counter these effects.
It is possible to have healthy growing plants with undetectable nitrate readings. Nevertheless a heavily planted tank with a low fish population (low fish population = insufficient nutrients provided by fish waste) and undetectable nitrates can lead to a nitrogen deficiency. Under these circumstances it is recommended to maintain nitrate levels around 5 ppm. Since Algone gradually adjusts the nitrate levels, maintaining specific levels can easily be achieved.
Some critics reading along may be thinking, “…well, it’s interesting, but I have free floating plants, that can’t rely on the substrate…”.
Going back to biology, nature in its complexity once again provides a solution. In short: aquatic plants are classified into 3 categories. Algae being the lowest followed by non-bloomers and bloomers. The higher plant will out-compete the lower.
As they also have a storing capacity for nutrients, it is sufficient to provide them with enough nutrients through the water column, without disturbing the aquariums’ balance.
Always remember that undetectable nitrate levels do not mean your plants are deprived of nitrates, the production of nitrates is continuous. No detectable nitrate means they are not excessive. Nitrate production however is constant in your tank.