CLOROX Pool&Spa Calcium Hardness Increaser for Pools, 4 lb — Raises Hardness to Prevent Corrosion & Etching

Clorox® Pool&Spa™ Calcium Hardness Increaser is a granular treatment designed to raise low calcium hardness in pool water, helping reduce corrosion, etching, and staining of plaster surfaces and equipment.

Maintaining the correct calcium hardness is a key part of balanced pool chemistry. When hardness is too low, water can become aggressive toward plaster, metal fittings, and other surfaces; when it’s too high, scale can form. This 4 lb pack from Clorox Pool&Spa supplies a measured, easy-to-use dose to boost total hardness in soft-water regions or after heavy dilution events, helping protect surfaces and extend equipment life.

How does this product protect my pool from corrosion and etching?

Low calcium hardness lets water pull minerals from plaster and metal, which can cause pitting, roughness, and weakened components. Adding calcium hardness increaser raises dissolved calcium levels so water becomes less aggressive, reducing the chance of surface damage.

• Raises total hardness to recommended ranges for plaster pools.
• Helps prevent mineral leaching from pool finishes and metal parts.
• Used after fresh fill or heavy dilution to restore balance quickly.

How do I use the 4 lb container safely and effectively?

The product is a granular formula meant to be dissolved or broadcast per label instructions; always test water before and after treatment. Follow the Clorox Pool&Spa directions for dosage based on pool volume and current calcium hardness, and ensure proper circulation when treating.

• Test total hardness with a reliable kit or the Clorox Pool app first.
• Add recommended amount in small increments and retest after circulation.
• Avoid adding directly to skimmer; broadcast evenly or pre-dissolve where advised.

Will this product cause cloudy water or scaling?

When applied at recommended dosages and with proper circulation, it is unlikely to cause cloudiness or scale. Overdosing or treating water already high in calcium can contribute to scaling, so measure and adjust carefully to keep levels within the ideal range.

• Follow dosage charts to prevent excessive calcium buildup.
• Combine with routine testing and pH/alkalinity control for best results.
• If cloudiness occurs, consider filtration run time and flocculation steps.

How does this product fit into my overall pool maintenance routine?

Calcium hardness increaser is one part of a multi-parameter approach to pool water care. Use it alongside pH, alkalinity, sanitizer, and stabilizer management to maintain balanced water that protects surfaces and equipment while keeping water comfortable for swimmers.

• Incorporate hardness testing into monthly water checks or after refill events.
• Use the Clorox Pool app for personalized dosage recommendations and troubleshooting.
• Maintain filtration and circulation when treating to distribute chemicals evenly.

Who this is for: This 4 lb Clorox Pool&Spa Calcium Hardness Increaser is aimed at pool owners with plaster or concrete pools and those living in soft-water areas, anyone who refills frequently, and service professionals who need a reliable, single-bag solution to raise total hardness and help protect pool surfaces and equipment. It’s appropriate for routine maintenance or corrective dosing when tests show hardness is below recommended levels.