To prevent limescale, from forming in the first place, Polti has created KALSTOP FP2003, the natural anti-limescale agent for steamers and steam generator irons. KALSTOP FP2003 derives from a natural product thus is biodegradable and nontoxic. KALSTOP FP2003 is made of tannate, reducing oxygen in the water, protecting against scale and corrosion, and protecting the metallic walls. Instructions: break open the phial and pour the content into the boiler of Vaporetto and Vaporella, previously filled with water. Stronger solutions can be used (e.g. 1 phial per litre of water) if the water is particularly hard. For the models with self-filling feature, we suggest to dilute the phial in 5 litres of water before pouring it in the tank.