Your swimming pool is prone to staining when left open and uncovered. Besides stains from naturally occurring copper and algae, debris blown into the pool can easily stain the concrete walls. Leaves are just one natural element you are bound to find floating in your pool as well as stuck to the bottom. Removing leaf stains may not be as difficult as you think.
Drain the pool and put on your gloves and goggles. The trisodium phosphate, strong base cleaner, can burn your eyes and should always be diluted with water. Put on your protective gear before opening the trisodium bottle.
Create the trisodium and water mixture by mixing 1 cup of water and only 1 ounce of trisodium phosphate. Mix with a wooden dowel. Even with gloves on, do not use your hands to stir it. The consistency should be pasty like cement.
Apply a layer about 3/8 inch thick across each leaf-stained area. Use the trowel or paint scraper to spread it over the stains. The trisodium phosphate will penetrate the stain and break up its components.
Allow the paste to dry for 24 hours and then use the paint scraper to remove the hardened mixture. Remove any stuck-on pieces with the nylon brush.
Hose the areas down and then rub the pumice stone on each leaf stain that remains.