Contrary to tropical plant waters, our tap water significantly lacks certain nutrients. Many essential plant nutrients and trace elements are missing or extracted during treatment in the water works. Yet if so much as one nutrient is missing, the plants stop growing and may even die (Leibig's law of the minimum). In order to ensure a healthy plant growth in the aquarium, the nutrient gap in our tap water must be filled and the water enriched so that tap water becomes good aquarium water.