Concrete and plaster pools can last for decades. However, concrete and plaster pools require routine maintenance, such as cleaning. Over a period of time concrete and plaster pool walls can become stained with algae and efflorescence. Efflorescence is a stain that results from salt and other mineral deposits that leak from the concrete and plaster. Muriatic acid is commonly used by pool cleaning professionals to remove these and other types of stains from a concrete or plaster pool. I have cleaned many pools over the years and my experience has led me to believe that in many cases, the homeowner can do the job themselves without the help of a professional. However, proper safety precautions must be taken.
Rubber gloves and boots
1) Completely drain the pool. Allow time for the concrete to dry.
2) Use the broom to brush away any dirt and debris from the walls and floor. Sweep up all the loose debris and remove it.
3) Spray the inside of the pool with a water hose. You want the concrete or plaster pool walls to be damp before you acid wash the pool.
4) Put on the safety gear. You want to wear rubber boots and gloves and safety goggles when working with muriatic acid.
5) Put one gallon of water into the plastic bucket. Add about 1/3 of a gallon of muriatic acid. You want to use a cleaning solution of approximately 3-to-1. Three- parts water to 1-part muriatic acid. Always add the acid to the water. Never pour the water into the acid.
6) Screw the brush onto the end of the pole. Dip the brush into the acid cleaning solution in the plastic bucket. Always keep the plastic bucket containing the acid wash solution on the ground. This is for safety reasons in case of a spill.
7) Scrub the pool walls and floor with the cleaning solution. Leave the acid cleaning solution on the walls for several minutes to let it soak in to the surface.
8) Spray the pool walls with the water hose to remove the cleaning solution. Only leave the acid solution on the walls for a few minutes before spraying it off. Set the water pressure on low so that you don’t splash yourself with the muriatic acid solution.
9) Use the procedures to clean the walls and floor of the entire pool. Repeat the cleaning process, if necessary. You may need to add more muriatic acid to make a stronger cleaning solution to remove tough stains. Increase the strength of the cleaning solution gradually and use only as much acid as is necessary. Never exceed a cleaning solution ratio that is stronger than 50-part acid to 50-part water ratio.
Muriatic acid is strong and can cause burns to exposed skin. It also produces powerful fumes that are dangerous if inhaled. Use care and caution at all times when handling muriatic acid.
Poolcenter.com: Acid Washing
Fire Your Pool Guy: How to Acid Wash a Swimming Pool (step-by-step)