How Do I Clean the Waterline Tile on My Pool?

Waterline tile picks up two different kinds of buildup. There is a soft, greasy scum line made of body oils, sunscreen and airborne dust, and there is hard white calcium scale that forms when the water is out of balance. The soft stuff scrubs off easily. The hard stuff does not.

Clean the soft scum line weekly and it never becomes a project. Let it sit and it bonds with calcium into something that requires far more work.

Weekly maintenance cleaning

1. Do this at your normal water level. No need to drain anything.
2. Use a stiff nylon tile brush on a short handle so you can put real pressure into it.
3. Work in sections of a few feet, scrubbing back and forth along the tile band.
4. For the greasy line specifically, a melamine foam pad (the magic eraser type) works extremely well and is safe on glazed tile.
5. Rinse the brush frequently so you are not just moving oil around.
6. Brush the walls just below the tile afterward to sweep loosened material toward the drain.

A commercial tile cleaner or a mild degreaser helps if the pad alone is not cutting it. Apply it to the brush rather than dumping it into the pool.

Removing calcium scale

If the deposit is white, chalky or crusty and does not budge with a brush, that is calcium carbonate scale.

For light scale, a dedicated calcium and scale remover applied to a damp cloth or brush and left briefly to work will usually take it off.

For heavier scale, a pumice stone works but only on hard, unglazed ceramic or stone tile. Keep both the stone and the tile wet at all times, work in small circles with light pressure, and never use pumice on glass tile, glazed tile, fiberglass, vinyl or plaster, because it will scratch all of them permanently. If you are not certain what your tile is, test in a hidden corner first.

For scale across the entire waterline, professional bead blasting is the right answer. It uses a soft abrasive media to strip the deposit without harming the tile, and it does in an afternoon what would take you a weekend with a pumice stone and a sore shoulder.

Stop it from coming back

Scale is a chemistry problem. Cleaning it repeatedly without fixing the water means cleaning it forever.

• Keep pH between 7.2 and 7.8, ideally 7.4 to 7.6. High pH is the main driver of scale.
• Keep total alkalinity between 80 and 120 ppm.
• Keep calcium hardness in a reasonable range for your surface, and do not let it drift upward unchecked through evaporation and top offs.
• Skim daily so oils and floating film get pulled into the skimmer rather than deposited on tile.
• A skimmer sock or a tennis ball floating in the pool absorbs surface oils and noticeably slows the scum line.

What not to use

Do not use a wire brush on tile. Do not use household bleach or ammonia based cleaners, which are hard to rinse and can react with pool chemistry. Do not use undiluted acid on tile without knowing the material, since it can etch grout and dull glazes. And do not use a pressure washer on tile that is set in old grout.

Waterline tile in the Florida Keys

Two things make waterline tile harder work down here. First, we swim year round, so sunscreen and body oil hit the tile band twelve months a year with no seasonal break. Second, the constant evaporation and frequent topping off in this heat concentrates minerals in the water, which pushes calcium hardness up and encourages scale.

Salt air adds its own fine crust to everything near the water, and pools without screen enclosures collect airborne dust and plant matter that binds into the oil line quickly.

If you have a saltwater chlorine generator, watch pH closely. Salt systems naturally push pH upward, and high pH is exactly what puts calcium on your tile.

Scrub the tile band the same day you brush the pool, because five minutes weekly is the difference between a wipe down and a bead blast.