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Use batch dosing when water is treated in defined tanks and the operator can measure, mix, wait and release each volume. Use continuous dosing when water flows without interruption and the chemical feed can be paced to verified flow and chlorine demand. A liquid metering pump usually offers tighter continuous control than dropping dry product directly into a variable stream. Dry or erosion feeding can fit selected systems, but it needs compatible granules, stable hydraulics and a validated residual check.

Store sodium thiosulfate pentahydrate sealed in a cool, dry, well-ventilated area, protected from water, direct sunlight and incompatible chemicals. Keep bags off the floor, inspect them for damage and moisture, rotate stock by lot, and reseal partial bags promptly. Do not assign a universal shelf life: use the supplier's package label, specification, SDS and batch documentation, then inspect or retest material that has exceeded the approved storage period.

Dechlorination is verified by testing the treated water, not by confirming that sodium thiosulfate entered the tank. Measure the chlorine form that controls the process, use a method with a suitable reporting range, analyze promptly, and compare the result with the facility's documented limit. If chloramine may be present, include total chlorine; free chlorine alone can miss combined residual.

For aquaculture dechlorination, treat incoming or make-up water before it reaches fish. Measure the chlorine species, calculate sodium thiosulfate for the supplied hydrate form and assay, mix completely, allow the validated contact time, then test the treated water against the facility's operating limit. When chloramine may be present, a free-chlorine result alone is not enough; total chlorine also needs attention.

To prepare sodium thiosulfate pentahydrate stock solution, define the final concentration in g/L, multiply by the final solution volume, and correct for the batch assay. Add water to the tank first, dissolve the weighed product under agitation, then top up to the final volume. Do not treat 10% w/v as the same as 10% w/w.

Sodium thiosulfate pentahydrate and anhydrous sodium thiosulfate supply the same thiosulfate salt, but they are not interchangeable by weight. The pentahydrate includes five water molecules and has a molecular weight of 248.18 g/mol. The anhydrous form has a molecular weight of 158.11 g/mol. At equal purity, 1.00 kg of anhydrous material is equivalent to about 1.57 kg of pentahydrate.