Prevents lime scale deposits on the walls and prevents the shutter filters SECAL prevents lime scale deposits and tartar on the pool walls, prevents the shutter filters including the filter cartridges. SECAL also protects the metal corrosion in contact with water. Compatible with sand filters, cartridge, diatomaceous, and filter bags. Instructions: Submit a pellet (without protective film) to 40 m3 of water in the skimmer basket after each washing of the filter. In case of busy water limestone, increasing the dosage.