Pool Mate 25-Pounds Premium Calcium Hardness Increaser - Rapidly

In this review the Pool Mate 25-Pounds Premium Calcium Hardness Increaser is assessed for pool owners who need a reliable way to bring low calcium levels into the recommended range. The bottom line: it is a straightforward, granular calcium chloride product that dissolves quickly and raises total hardness effectively when used as directed, making it a practical choice for vinyl, tile, fiberglass and painted pools that show signs of low hardness or early etching.

Key Features

• 100% calcium chloride: A pure formulation that targets calcium hardness without adding unnecessary additives, helping restore the recommended hardness range.
• Rapidly increases hardness: The granular formula dissolves quickly so users see measurable changes after treatment and circulation.
• Prevents corrosion and etching: Proper calcium levels reduce the risk of surface etching and metal corrosion caused by soft water.
• Easy dosing guidance: The product includes a chart and clear bucket-dilution instructions for safe application to avoid overfeeding.
• Precise strength: 8 ounces raises calcium hardness about 10 ppm per 5,000 gallons, allowing controlled adjustments for most residential pools.

Who It's For

This product is best for homeowners and maintenance technicians who regularly test water and need to correct low calcium hardness in vinyl, tile, exposed aggregate, marcite, fiberglass or painted pools. It fits well into a routine water balance regimen when paired with a reliable test kit and functioning circulation system.

It is not ideal for users who do not test water or who are unwilling to follow dilution and dosing instructions; those users should seek professional pool service or a pre-measured system if they need hands-off maintenance. Also, users with extremely small or very large specialty commercial systems should consult specific recommendations before use.

Pros & Cons

Pros

• Effective at raising calcium hardness to the recommended range when dosed correctly.
• Good value for the amount provided, offering predictable ppm increases per 8 ounces.
• Dissolves quickly and works even in cooler water, so treatment can be completed without long delays.

Cons

• Some users report difficulty opening the container lid, making first use inconvenient.
• Requires careful measuring and dilution; incorrect dosing can lead to uneven hardness results.

Specifications

Our Verdict

The Pool Mate 25-Pounds Calcium Hardness Increaser is a reliable, cost-effective option for pool owners who test and manage their water chemistry. It delivers fast, measurable increases in hardness and helps prevent surface etching when used with the included dilution and dosing instructions, making it a practical purchase for most residential pools.

Frequently Asked Questions

How much does 8 ounces change hardness?
About 10 ppm per 5,000 gallons when added and circulated as directed.

How should it be added to the pool?
Dissolve in a plastic bucket of pool water (up to 2 lb per 5-gallon bucket) and slowly pour around the pool while the pump runs.

Which pools need this product?
Use for vinyl, tile, exposed aggregate, marcite, fiberglass or painted pools that test below the recommended calcium hardness ranges.