Acid Washing a Concrete Pool
Drain the pool with a submersible pump. Ultra Modern Pool & Patio has pumps which can be rented or purchased. Before draining your pool, you should be thoroughly knowledgeable about pool flotation due to hydro-static pressure. When a pool is emptied for painting or other work and then left for a period of time, the existing underground water pressure or water-soaked soil presses so hard upon the empty shell that it literally floats out of the ground.
Use a separate pump, that is, not the pump from the re-circulation system. Carefully monitor the discharge water to make sure that lawns and shrubs are protected. Once the water level reaches the floor, acid washing can begin.
Remove all winterizing plugs and make sure the skimmers are drained. Once the water level is low enough to wade into the deep end, remove all hydro-static relief plugs. If the pool will be empty and the hydro-static plugs will not come out, you should open them. This is very important when acid washing. If there is a high water table under the pool and too much water is removed, the pool may pop out of the ground.
After the pool is empty, plug the pipe in the main drain. You do not want the acidic water getting in the main drain pipe. Do not leave the plug in the main drain or the pool empty longer than necessary as the pool could float if the water table comes up.
Always add acid to water, not water to acid. Follow all safety guidelines and precautions when working with acid. Work with someone else in case of emergency.
Mix three parts water to one part acid. Mix two to one for more etching effect. One gallon of 10% acid solution will acid wash 200 square feet of pool surface.
Wear rubber gloves, boots, and eye protection.
Use an acid brush with a handle, and work with small areas, hose down in one to five minutes. Wash a section of 100 square feet at a time. After washing each section, flush thoroughly with water.
If you get any acid on you, splash with water. If any gets in eyes, flush eyes thoroughly with water. It is a good idea to have the garden hose close by and water running while you are working.
You need to neutralize the standing water in the bottom of the pool with soda ash (pH increaser.)
If you are going to paint, you will need to follow with #910 Olympic Pool Washing compound. The pool washing compound neutralizes the acid left on the walls so that the paint can adhere.
After completing the acid washing, flush all pumps with clean water to prevent deterioration of equipment.
Download a printable PDF: BUL-145 – ACID WASHING A CONCRETE POOL
NOTE: It is illegal to pump water in the street if you live in the city. You should leave the water in the pool and neutralize it with soda ash. Then test the pH and when it is 7.6 or above, it is okay to use it for irrigation water.
NOTE: Always follow label directions and manufacturer’s instructions for each product used. Conditions may vary from pool to pool. Ultra Modern Pool & Patio does not assume any responsibility or liability for the results that may be obtained through utilization of this or any other program, procedure or product.
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