Q: What is the white film that we are getting on our tiles and grout in our swimming pool?
A: If you pool has white deposits on tile or other surfaces in your pool or spa, it is most likely caused by efflorescence, which is caused by calcium and mineral salts, which you often find while concrete, marcite/pebble, or grout are curing. The minerals deposit on the surface – and this is completely normal. It can typically be taken off with a gentle scrub of a muratic acid/water solution, or in cases where the surface is dyed (such as in our colored rocks and waterfalls) a cleaning with a weaker solution that won’t take the color out and a wire brush.
To prevent this from happening in older pools it is important to keep the water chemistry in balance including the calcium hardness, alkalinity and pH.
Here’s a bit more of the technical information for those of you who wonder: [source – wikipedia]
Primary efflorescence is named such, as it typically occurs during the initial cure of a cementitious product. It often occurs on masonry construction, particularly brick, as well as some firestop mortars, when water moving through a wall or other structure, or water being driven out as a result of the heat of hydration as cement stone is being formed, brings salts to the surface that are not commonly bound as part of the cement stone. As the water evaporates, it leaves the salt behind, which forms a white, fluffy deposit, that can normally be brushed off. The resulting white deposits are referred to as “efflorescence” in this instance. In this context efflorescence is sometimes referred to as “saltpetering.” Since primary efflorescence brings out salts that are not ordinarily part of the cement stone, it is not a structural, but, rather, an aesthetic concern.