How to remove calcium from pool tile

Evaporation and water chemistry. As water evaporates at the waterline it leaves calcium behind, and high pH, high alkalinity and high calcium hardness make it come out of the water faster. Waterfalls and spillovers splash and dry over and over, so they scale up quickest. Hard fill water adds to it.

White, flaky scale is calcium carbonate, the easy kind. It fizzes if a drop of acid touches it and comes off with a pumice stone or a scale remover. Hard gray or blue gray scale that does not fizz is usually calcium silicate, which builds up over years and is much harder to remove.

Scale on the tile is a different problem from stains in the plaster below it. Those are what an acid wash is for.

Start gentle and work up. Test any method on a corner first.

• Pumice stone, wet, on glazed ceramic or porcelain tile. Not on glass tile, which it scratches.
• A tile and scale remover gel made for pools, brushed on with a nylon brush and rinsed, following the label.
• A specialist for hard scale. Thick silicate scale is usually removed by bead blasting, a separate specialty service done by tile cleaning companies.

After any acid based product, recheck the pH and alkalinity.

Vinegar works on light white scale, slowly. Muriatic acid works faster but is strong enough to damage grout and hurt you, so it needs gloves, eye protection and a lot of care. The CDC chemical safety rules apply: never mix it with anything, and keep it away from chlorine. For most people a pool tile scale remover is the safer choice.

Not with a normal pressure washer. Calcium scale is bonded to the tile and water pressure will not shift it, while it can blow out grout. The professional version, bead blasting, uses fine media at low pressure and is a specialty job.

Keep the chemistry in range and clean the tile line often.

• Hold pH between 7.2 and 7.8 and calcium hardness around 200 to 400 ppm. See pool chemical levels for Florida.
• Clean the tile line every week so fresh deposits never harden.
• Use a scale inhibitor if your fill water is hard.
• Keep the water level steady, so the waterline does not sit at a new height and scale up a fresh band of tile.

Spraying and brushing the tile line is part of every weekly pool service visit.

It makes the tile line rough and dingy, and scale inside the system is worse than scale you can see. It coats salt cells, which then make less chlorine, and builds up in heaters. On plaster it can show up as rough white nodules. More on salt cells in salt water vs chlorine.