In the context of aquariums, potassium is an essential nutrient for aquatic plants. It is one of the macronutrients required for plant health, alongside nitrogen and phosphorus.

• Yellowing of Leaves: Older leaves often start yellowing, especially around the edges, which is known as chlorosis.
• Pinholes in Leaves: Potassium-deficient plants can develop small holes in their leaves, which may eventually spread.
• Poor Growth: A lack of potassium results in stunted plant growth and weak, fragile stems.