Spa water hardness products

• To increase hardness: Add calcium booster in small doses, pump running, wait 10–15 min, retest until target is reached.
  
• To lower hardness: There is no effective calcium “reducer” — dilute (partially drain + refill) then rebalance pH and total alkalinity. Anti-limescale/sequestrants help prevent scale but do not lower hardness.
  
• Signs of too low hardness: “aggressive” water, tendency to foam, risk of corrosion (metal/exchanger).
  
• Signs of excessive hardness: white deposits, cloudy water, clogged filter, limescale lines.

• Targets: pH 7.2–7.8 · Total alkalinity 100–150 ppm · Calcium hardness 100–200 ppm
  
• Order: Alkalinity → pH → Hardness. Adjust only one parameter at a time. Wait 20-30 minutes between each product.

• Use strips or a liquid kit (more accurate).
  
• Frequency: 1×/week, and always after a long swim or adding product.
  
  

This is the amount of dissolved calcium in the water. Proper hardness protects the acrylic, heat exchanger, and metal parts. Indicative targets: 100–200 ppm for spas. Too low → “aggressive” water, risk of corrosion and foaming; too high → limescale deposits (white marks), cloudy water, and clogged filters.