<p>Plants (including algae) require three macro nutrients to grow: Nitrogen, potassium, and phosphorous. Of these three, phosphorous is the often the "growth-limiting" nutrient. i.e. the local environment may have an abundance of nitrogen and potassium, but algae won't develop unless phosphorous is available too. </p> | <p>Plants (including algae) require three macro nutrients to grow: Nitrogen, potassium, and phosphorous. Of these three, phosphorous is the often the "growth-limiting" nutrient. i.e. the local environment may have an abundance of nitrogen and potassium, but algae won't develop unless phosphorous is available too. </p> |