What does an Acid Wash Do?
Also known as an acid bath, or “drain and clean”, an acid wash removes impossible stains by scouring off a thin layer of the pool’s lining. The acid used is called Muriatic acid and must be handled with care. This method of pool cleaning should not be done regularly and is reserved as a last resort. Also, pools made of fiberglass and vinyls are not suitable candidates for acid washing. Doing the wash yourself can help you save a few hundred dollars, but is a dirty and laborious process. Protective gear such as pants, a mask, safety glasses, rubber gloves and boots should be worn during the process. For about $150, you can learn how to acid wash a pool and do the procedure yourself.
Signs You Need Acid Washing:
If the water is clear enough to where you can see the pool floor, chances are the pool can be restored with a bit of work. Through the use of chemicals, tools, and proper filtration, most pool liners can be brought back to their former glory. Before considering acid washing, you can try using a pressure washer on the stains. Another option is to use a diluted 3:1 mix of acid/water on a sample area to test effectiveness. If stains are recurring frequently, the problem must be taken care of before cleaning, otherwise it will simply return. Checking the chemistry of the water for metal, calcium and TDS content can help detect a chemical-based stain issue.
Stains caused by algae can be very hard to remove, making acid washing the only option. Pools plagued by algae can be restored by replacing the pool water and follow up with an acid wash. Other stains caused by minerals (hard water), dirt, and even chlorine can be removed with acid to improve the look of a pool liner dramatically. Just remember, this procedure removes a bit of the liner, which is about 1/2 inch in thickness. Plaster linings such as those made of marcite and white-coat can handle several washings before too much has been eroded.
Again, this is real acid you will be dealing with. Although it will not burn through the skin immediately like some science fiction slime, it is important to minimize contact and remove it when you do touch it. Breathing devices rated for fume protection should be used, as well as full body suit. The pool floor should be coated in soda ash to capture and neutralize the acid for safe disposal. The acid can cause wounds to sting and should be washed away with water upon first contact. Eye contact should be followed up with rinsing for up to 15 minutes. It’s always a good idea to have a helper nearby during the course of the project.
- Step 1: Prep the Pool
Drain the pool. Pick up and remove any physical debris such as leaves and mud. Using a long brush, scrub the pool liner using TSP (Tri Sodium Phosphate), which is a powerful cleaner. After each section is cleaned, immediately hose it down with water, taking care to not allow the TSP to dry on the walls. Follow the mixing instructions carefully. Finally, scrub the floor and give it a final wash.
- Step 2: Mix the Muriatic Acid
Pour some of the Muriatic acid into a plastic bucket, mixing it with water at the proper ratio. Add the water first, followed up by the acid. Cover your hands with rubber gloves and your eyes with safety glasses. As the instruction should say, never exceed a Muriatic concentration of 10 percent. A single gallon of solution can be expected to cover approximately 100 square feet.
- Step 3: Washing
Apply soda ash to the bottom of the pool to neutralize the acid. Use your long brush to apply the Muriatic solution to the liner. You can use a combination of circular and back/forth strokes. The acid will bubble on the surface as the surface layer is removed. When the bubbling dies down (about 30 seconds), follow up with a rinse of water. As with the TSP, it is important to not let Muriatic acid dry on the walls. If it sits too long, it can burn through too deep. The soda ash and water at the pool floor will neutralize the acid and prevent it from eating away at the floor. Make your way around the pool walls, etching the floor last. When complete, the lining will feel noticeably rougher, like the feeling of sandpaper.
- Step 4: Final Wash
Wash and scrub the pool again scrubbing and washing in sections. The remaining acid must be neutralized. You will have a large collection of acid and water sitting at the pool bottom. Apply a mixture of soda ash to the floor (2lbs ash/ 1 gallon water). Stir the mixture with a pole brush. Now you can use a portable pump to remove the puddle and pump it to a safe location (dirt is best, as the chemicals can damage plants like grass). Pump it in a spot where no animals or children can access. A good practice is to slowly add water to the pool as you are pumping. This dilutes the mixture as it is drawn away, preventing a ring from forming.
Alternative: Hire a Professional
This laborious procedure can go wrong quickly if you are not on the ball at all times. Hiring a professional crew is the most stress-free option, as these companies are trained in this field. They have the tools and experience to get the job done in a single day.