Gunite/Marcite Pool Acid Washes

Gunite and marcite are two of the most popular materials for the interior surfaces of home swimming pools. Gunite is a mixture of cement and sand. Marcite is also known commercially as plaster or whitecoat, and it may or may not include quartz. Both gunite and marcite pools can by cleaned by a technique called acid wash. Acid washing your pool can remove algae, chemical stains, and mineral deposits.

In order to acid wash your pool, you must have all the water in your pool removed. Elkhart Pools can drain your pool safely, as can the water company in your city. Do not attempt to drain all the water from your pool by yourself, even if you are experienced at making repairs. At Elkhart Pools, we are happy to perform the acid wash for you, from beginning to end, but if you prefer to do it yourself once you have had the water drained, you can come to us to get the necessary supplies.

​If you do your own acid wash, it is important to wear appropriate safety gear, including a breathing mask, goggles, rubber gloves, and slip-proof boots. First, scrub the walls and floor of the pool with a brush to remove the visible debris. Next, pour a gallon of water and a gallon of muriatic acid into a bucket, and keep adding one gallon of each until the bucket is almost full. Pour a small amount of the acid solution on the wall to test it. If it has enough acid, it will bubble on contact; if it does not bubble, add more acid to the solution, one cup at a time. Pour the acid from the top of the wall and scrub the wall with a brush. When the acid runs down to the bottom of the pool, neutralize it by adding two pounds of soda ash per gallon of acid. Finally, pump the mixture of acid, water, and soda ash out of the pool. Then rinse the pool several times with a hose and pump the rinse water out of the pool. After you have done this, you are ready to have your pool refilled with water. You may wish to resurface the pool with gunite before you refill it with water. Be sure that the pH of the water, as well as chlorine and acid levels, are appropriate for swimming before anyone uses the pool.

If your pool has a marcite lining, the acid wash process is similar to the one used for pools with gunite linings. If your pool has a vinyl lining, do not acid wash it, as this will damage the vinyl. To remove algae and stains from the vinyl lining of a pool, use detergents designed specifically for vinyl pool linings. It is also not necessary to drain all the water from a vinyl-lined pool when cleaning it. If the vinyl lining of your pool will not get clean, even when you scrub it with the appropriate cleaning products, it is necessary to replace the vinyl lining.