Activator D The easier, safer, more economical and effective way to treat and maintain the sparkle in your pool! The product comes in two bottles - a powder and a liquid - totaling 850 grams. This is enough for a 50,000 liter pool for one month. It is safe, environmentally friendly, economical and very effective. A neglected pool will need a double-dose to start off, but this will effectively kill the algae and clear the water in a few days. Black algae will disappear over a few weeks, and should be brushed off the walls. (Chlorine does not kill algae, only bleaches it; this is why during a storm the chlorine is drawn from the water and the algae is once again visible, turning the water green.) Activator D does not hurt eyes or skin, and swimming costumes last longer. It is environmentally friendly, non-toxic, non-corrosive and chlorine-free, and pool run-off water should not damage plants.