Flourish Phosphorus, 4 L / 1 fl. gal. Phosphorus supplement for the planted aquarium Phosphorus is one of the main three macro nutrients required by plants and can often be the limiting factor to growth in a flourishing system A safe solution of potassium phosphate that takes the guess work out of phosphate dosing When used as directed Flourish Phosphorus will enhance and accelerate the growth of aquatic plants without enhancing algae growth 250 milliliters treats 500 to 5000 US gallons