... etching caused by low alkalinity. Stabilizes pH balance in pool water and eliminates the demand for unusually large amounts of pH ... new repacking styles. Size:0.5kg(or 1lb),1kg(or 2lb),2kg(or 5lb),3kg,4kg(or 10lb),8kg and 10kg of Pillow Bags ... ,4kg (or 10lb),8kg and 10kg of Pails, Jars, Jugs,Pots,Tubes,Drums and etc. 25kg or 50lb bags Sodium Bicarbonate for water treatment