Calcium typically forms and becomes visible on swimming pool tiles at some stage in the life of almost every pool. It is a very common issue that pool owners face for various reasons. To help you understand why calcium is forming on your pool tiles the following information may be of help.
When tiles get wet, the water evaporates which leaves any calcium and minerals in the water to solidify on the tiles. This picture shows what calcium looks like on waterline tiles. This type of calcium formation is unavoidable as it is a simple function of chemistry. This occurs because the calcium in your water needs to go somewhere after the water evaporates. Calcium chloride is always present in balanced water and this calcium will become visible on most surfaces after evaporation occurs, particularly if your calcium hardness level is high. This type of calcium formation will almost always happen on waterline tiles (and water feature tiles) due to heat, wind and fast evaporation, particularly in summer. If the pH of your water is consistently high, this will accelerate the formation of calcium on your pool tiles.
Calcium can seep out through the cement that binds the top coping tiles (horizontal tiles at waters’ edge) above the vertical waterline tiles. Without doubt this is the most common cause of calcium formation in swimming pools. In this case, the calcium formation comes from the chemical reaction within the cement. This type of calcium is called calcium hydroxide and is often produced during the hydration (curing) of cement. White cement is made with around 31% calcium and this can cause calcium scale in tiles (particularly when moisture is present) to seep out of the joints and into the pool. This calcium will often start right under the coping tiles and run downward toward the water. This type of calcium is very hard and is often quite thick in places.
The final way calcium can form on tiles is in a single thick band along the waterline. If your pool design means that the water level is the same year-round (because of an infinity edge, indoor pool or an auto top-up device) then it is very likely that you will see this happening in your pool. In these cases, the water level does not move up and down like ordinary pools and this causes the calcium to form a very hard horizontal band at the static waterline. Brushing the waterline tiles regularly and, if possible, adjusting the water level will help reduce the formation of calcium on your pool tiles.
The best way to clean swimming pool ties is to treat your pool for several weeks with our calcium dissolving products. It is best to do this before trying to remove it manually. This is because our treatments soften hard calcium which makes removal much easier and simple to do. If you attempt to remove calcium without our pre-treatment is as hard as concrete and strongly adheres to the tiles. This means that you will likely cause severe damage to the tiles in trying to scratch it off. This can lead to chipped, scratched and broken tiles. We do not recommend using rubbing blocks, paint scrapers or pumice stones on tiles as these can scratch or crack the tiles permanently. Our calcium treatment kit is the best treatment option for softening waterline calcium buildup on swimming pool tiles.