Phosphorus is the nutrient that most influences the growth of algae in lakes. An increase in the concentration of total phosphorus in lake water generally indicates a potential increase in biological productivity. Tracking in-lake phosphorus levels over time is another way of monitoring changes in lake water quality. Combined with Secchi transparency readings, phosphorus data provides additional information about lake ecosystem dynamics. Readings below 6 ppb (parts per billion) are considered very good; at values greater than 10 ppb there is potential for problematic algae bloom.