SpaGuard® Calcium Hardness Increaser – 12 fl oz Raises Calcium Hardnes – Hot Tub Things Skip to content

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  • SpaGuard® Calcium Hardness Increaser is designed to raise calcium hardness levels in spa water when they fall too low, helping prevent corrosion of equipment and surface etching.

  • The granular or liquid formula dissolves quickly in circulating spa water and delivers measurable increases: for example, “1 tablespoon per 100 gallons increases calcium hardness by ~25 ppm.” 

  • Maintaining proper calcium hardness (typically ~100-200 ppm for spas) helps protect plumbing, jets, surfaces and prevents foaming or water that feels “soft.” 

  • Compatible with all spa sanitizing systems and easy to use—just test water first, then broadcast the product while the circulation is running. 

  • Ideal for spas located in soft-water areas or where water replacement or fill has resulted in low calcium levels.