Acid washing is a deep-cleaning process that removes buildup and staining from a pool's surfaces, including the tiles. Here is a list of tasks typically performed during an acid wash by a pool cleaning service:

1. Preparation: Before the acid wash, the pool cleaning service will cover any nearby plants or other sensitive areas to protect them from the corrosive effects of the acid. They will also make sure the pool water is properly balanced and that the pumps and filters are working correctly.

2. Drain the pool: The pool will be drained to expose the surfaces that need to be cleaned. This allows the cleaning service to focus on the tiles, deck, and other surfaces without having to work around water.

3. Mix the acid: The cleaning service will mix the acid and water in the appropriate proportions, following the manufacturer's instructions. They will then pour the solution into the pool.

4. Apply the acid: The cleaning service will use a spray bottle or other equipment to apply the acid solution to the tiles, deck, and other surfaces. They will use brushes or scrubbers to work the solution into the surfaces, removing buildup and staining.

5. Rinse the surfaces: Once the acid has had a chance to work, the cleaning service will rinse the surfaces thoroughly with clean water to neutralize the acid and remove any remaining residue.

6. Fill the pool: The cleaning service will fill the pool with fresh water and adjust the water chemistry to ensure it is safe for swimming.

7. Inspect the pool: Before leaving, the cleaning service will inspect the pool to make sure it is clean and safe. They will also provide advice on how to maintain the pool to prevent future buildup and staining.