Nil-Phos Plus acts by bringing phosphates together allowing them to be filtered out by your filtration system. It is formulated at optimum strength to ensure rapid removal of phosphates. It is simply added to the water or directly to the skimmer box. Continue to run your pool filtration to remove the phosphate. Thanks to the inbuilt clarifier, you will also clear your water at the same time saving you time and money. Once the pool clears, we recommend you also run a quick backwash to ensure phosphates do not re-enter the pool.