What Is Pool Acid Wash?

What Is a Pool Acid Wash?

A pool acid wash — also called a drain and clean — is a process where the pool is drained and a diluted solution of muriatic acid (hydrochloric acid) is applied to the pool’s interior surface. The acid dissolves a thin layer of the plaster or cement finish, removing embedded stains, algae, mineral deposits, and discoloration to reveal a cleaner surface beneath.

How the Acid Wash Process Works

The acid wash procedure follows a specific sequence:

1. Drain the pool: All water is pumped out, and any debris at the bottom is removed
2. Pre-wet the surface: The pool walls and floor are hosed down to keep them wet, preventing the acid from reacting too aggressively in any one spot
3. Apply acid solution: A mixture of muriatic acid and water (typically 50/50) is poured or sprayed onto sections of the pool surface, working from top to bottom
4. Scrub and rinse: Each section is scrubbed with a brush and then rinsed with water before the acid can over-etch the surface
5. Neutralize: After the entire pool is washed, a soda ash (sodium carbonate) solution is applied to neutralize any remaining acid
6. Pump and refill: The acid water is pumped out, properly disposed of, and the pool is refilled with fresh water

The entire process typically takes one full day for a standard residential pool.

When Is an Acid Wash Needed?

An acid wash is appropriate when:

• The pool surface has persistent stains that chemical treatments cannot remove while the pool is full
• Green or black algae has penetrated the plaster surface and will not respond to shock treatments
• Mineral staining (iron, copper, manganese) has discolored the finish
• The pool was neglected and sat green for an extended period
• The finish has turned gray, dull, or dingy from years of use

An acid wash is not appropriate when the plaster is already thin, heavily etched, or showing exposed aggregate where it should be smooth. In those cases, resurfacing is the correct solution rather than removing more material.

Acid Wash Limitations

Each acid wash removes approximately one-sixteenth of an inch of plaster material. A pool can typically handle two to three acid washes over its plaster’s lifetime before the finish becomes too thin and requires resurfacing. It is a cosmetic refresh, not a repair — it does not fix cracks, delamination, or structural issues.

Acid Washing in Central Florida

Central Florida pools are particularly prone to the staining conditions that lead to acid wash needs. The combination of high mineral content in local water, warm temperatures that promote algae growth, and year-round pool operation means finishes stain faster here than in cooler climates. Many Orlando-area pool owners schedule an acid wash every 3 to 5 years as part of their long-term pool maintenance plan.

An acid wash also exposes any tile or structural issues that were hidden when the pool was full, making it a useful diagnostic step before deciding on further tile or resurfacing work.