Dichlor
Dichlor (sodium dichloroisocyanurate) is a fast-dissolving stabilised chlorine product that adds both free chlorine and cyanuric acid to pool water.
Definition
Dichlor (sodium dichloroisocyanurate) is a fast-dissolving stabilised chlorine product that adds both free chlorine and cyanuric acid to pool water.
Typical Values: Available chlorine: ~56%; CYA added: ~33% by weight of product
In Plain Language
Dichlor contains approximately 56% available chlorine and about 33% CYA by weight. It dissolves very quickly — faster than trichlor — making it useful for quick FC increases. However, every pound of dichlor adds a significant amount of CYA. Repeated use as a primary sanitiser or shock product leads to CYA accumulation. Dichlor is best used sparingly for quick chlorine boosts rather than as a primary or shock product.
Why It Matters
Many pool owners use dichlor shock repeatedly without testing CYA, leading to CYA accumulation that eventually makes the pool unsanitisable.
Typical Values
Available chlorine: ~56%; CYA added: ~33% by weight of product
Last reviewed: 2026-06-01