The Hasa 60050 is a 50 lb Alkalinity First Bag. Alkalinity and pH adjustments are necessary to maintain a chemical balance so that sanitizers such as chlorine will act efficiently to provide a healthy bathing environment, free from bacteria and algae. HASA HI-TEMP SPA pH INCREASER raises spa water alkalinity and pH to maintain that proper balance. Proper ranges of alkalinity and pH will provide the most comfortable spa usage by reducing eye, skin irritation and damage to your spa surface or your spas equipment caused by acidic conditions. A proper pH range is between 7.2 and 7.8; a proper alkalinity reading should be between 100 and 120 ppm.