Roam Descalix contains methanesulfonic acid, a strong organic acid with excellent solvency power that makes it highly effective at dissolving mineral deposits.

An acid removes these deposits by reacting chemically with the minerals that form them. In horticulture, the deposits are typically lime from hard water or precipitated fertilizers, which build up into a hard layer inside gutters, pipes, and irrigation systems and cannot be removed with water alone.

When the acid is applied, it releases hydrogen ions (H⁺). These ions react with the mineral compounds in the deposit, converting the solid layer into soluble compounds and loosening it from the surface.  Once the scale comes loose, the dissolved dirt can be rinsed away quickly and easily.