This can be caused by various factors: lime deposits, a fault in the filtration circuit, neglect of the treatment of the water in your jucuzzi tubs, etc. But since the origin is variable, there are also many remedies. Water naturally rich in limestone This is the most common case. Swimming pool waters are hard, that is to say, naturally rich in calcium and magnesium. This explains the whitish or grayish deposits on the surface of the water and the formation of scale in the pipes. If this is the case with your spa water, the first thing you need to know is its lime content. This has a real effect: on the efficiency of disinfection; on the spread of algae; and above all, on the longevity of your device in general. Here are the 3 key indicators that allow you to monitor water quality: the Hydrotimetric Titer (TH) for hardness; pH for acidity; and the TAC for total alkalinity. Test kits are available in stores. Prevention: anti-lime product and controlled pH To neutralize limescale, use anti-limescale products or limescale inhibitors. If lime and scale are already present, the only solution is to drain your spa tub and thoroughly clean the walls and equipment (pipes, filter, etc.) to remove all traces of tartar plaques. If the case is really serious, you may need to change the upholstery. To prevent all this, check frequently (at least once a week) knowing that the ideal pH is between 7.2 and 7.4, and that the pool water should not exceed 28 ° C too much. . Also, don't forget to disinfect the water using appropriate products.