Sodium Bi Sulphite Monohydrate

Sodium bisulphite powder (CAS 7631-90-5; in commerce the solid is largely sodium metabisulphite, Na2S2O5, which turns into bisulphite as it dissolves) is the powder form of the pool chlorine neutraliser, supplied by Global Chemicals LLC at 95% minimum purity as a white to off-white crystalline powder in 1 kg, 5 kg and 25 kg bags from stock in Muscat. It does the same job as the liquid, converting free chlorine to harmless chloride within minutes, but it stores for years without losing strength, weighs a fraction of the equivalent liquid, and is dosed by the gram, which is why pool-service companies carry it on the van and facilities managers keep it in the plant room for emergencies.

Dosing. Dissolve the powder in a bucket of pool water and pour the solution around the pool with the pump running. The working rate is 70–100 g per 10,000 litres for each 1 mg/L of free chlorine to be removed, a deliberate margin over the stoichiometric 15 g; wait 30 minutes, retest, and add a second, smaller dose only if chlorine is still above target. Work in steps rather than one large dose: an overdose drives chlorine and ORP to zero and leaves the water unprotected until chlorine is re-established. The reaction lowers pH slightly, so check pH and alkalinity afterwards.

Uses: reopening a pool after shock treatment, correcting over-chlorination from a pump or controller fault, neutralising water before drain-down to a drain or garden, protecting liners, handrails and seals from sustained high chlorine, and resetting water chemistry before treatments that chlorine would break down. For continuous dechlorination in water-treatment plants and reverse-osmosis pre-treatment, see the water-treatment sodium bisulphite page.

Storage and handling: keep bags sealed and dry; the powder absorbs moisture and oxidises slowly to sulphate if left open, and it smells of sulphur dioxide. Store it away from acids and from chlorine products, which release sulphur dioxide on contact. Wear gloves, goggles and a dust mask when weighing. Every bag carries a GHS safety data sheet and certificate of analysis.

Delivery is same day within Muscat, next day to Sohar, Salalah and Duqm, and by road across the GCC with a certificate of origin. Request a quote with the pack size and quantity.