Pool tile guide Bead blasting vs. acid wash.

They clean different parts of the pool

Bead or media blasting is for the tile: the band at the waterline, raised spa walls, spillways and stone features. It knocks calcium scale off hard surfaces. See pool tile cleaning and calcium removal.

An acid wash is for the plaster: the floor and walls below the tile. It lifts stains and dullness from the surface of the plaster. See plaster acid wash.

How each one works

For tile cleaning, the water is lowered about 6 to 12 inches below the tile line. The pool is not drained. A fine media is sprayed at the tile at low pressure to remove the scale, and then it's vacuumed out with separate pumps, so nothing goes through your equipment.

For an acid wash, the pool is drained, the plaster is washed to lift stains, the surface is neutralized, and the pool is refilled. Because plaster is thin, acid washing should be occasional, and the surface should be checked first.

Which one do you need?

If the problem is a white or gray line on the tile, you need tile cleaning. Tile cleaning won't remove plaster stains.

If the problem is stained, blotchy or dull plaster, you need an acid wash, or a replaster if the plaster is rough or worn through. Many pools need both, and they can be quoted together from the same photos.

What about acid on the tile?

Brushing acid onto tile scale is sometimes suggested as a shortcut. It tends to work unevenly on hard scale, can etch some tile and grout, and doesn't reach the buildup on rough surfaces like stone. Blasting removes the scale mechanically instead.