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Spa Calcium Hardness Increaser, 12 oz, Single Pack

Based on 3,939 reviews
Condition: New
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$8.99
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Availability: In Stock.
Fulfilled by Amazon

Arrives Nov 10 – Nov 11
Order within 14 hours and 36 minutes

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At a glance

Condition
New
Size
12 oz (Pack of 1)
Model
BIO42257
Weight
12 oz
Item Form
Powder
Product Benefits
Prevents Corrosion
Package Size Name
Single Pack

Features 5

  • Boosts Calcium Hardness: SpaGuard's Calcium Hardness Increaser enables spa owners to increase their calcium hardness with this easy to use granular formula, which will boost your calcium hardness to above the danger zone, where low levels cause extensive corrosion of plumbing, jets, fixtures, and tub surfaces.
  • Keeps Optimal Calcium Level: It helps raise the calcium level steadily to the optimal calcium hardness level of 200-400 ppm, to keep the spa water from becoming corrosive to heating elements and other equipment.
  • Protects Spa & Equipment for Longer Life: This helps protect your hot tub against corrosion, extending the life of your equipment and hot tub surfaces.
  • Compatibility: Calcium Hardness Increaser is compatible with chlorine, bromine, ozone and biguanide sanitizers.

Description

SpaGuards Calcium Hardness Increaser enables spa owners to increase their calcium hardness with this easy to use granular formula. This product will boost your calcium hardness. Low levels cause extensive corrosion of plumbing, jets, fixtures, and tub surfaces. Calcium Hardness Increaser will help raise the calcium level at a steady but not create scale build-up and cloudy water. The optimal calcium hardness level is 200-400 ppm, while anything below 100 ppm will cause corrosion. Raises calcium levels. 1 tbs. per 100 gallons increases calcium hardness-25ppm Prevents corrosion of equipment due to low calcium hardness Prevents etching of plaster due to low calcium hardness. When you use BioGuard spa care products (SpaGuard or Soft Soak), you are enlisting a group of individuals whose expertise is unsurpassed in the spa and pool industry. Whose dedication to helping you achieve perfect water no matter what the individual circumstance is their number one priority. Whose sole purpose is making your spa or pool the most enjoyable and trouble-free experience that you and your family will ever have. Whose dedication to the innovation and history of new product introductions is never matched, but often imitated. This dedication to service and the relentless pursuit of perfect water is inherent in the DNA of every BioGuard dealer.

Specs 15

Brand SpaGuard
Item Weight 12 ounces
Item Form Powder
Product Benefits Prevents Corrosion
Brand Name SpaGuard
UPC 017541612326 017541646123
Number of Packs 1
Package Size Name Single Pack

Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Nov 10 – Nov 11

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

  • Klarna Financing
  • Affirm Pay in 4
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  • Zip Pay in 4
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  • Financing through Google Pay
Leasing options through Acima may also be available during checkout.

Learn more about financing & leasing here.

Top Amazon Reviews


Great value
Size: 12 oz (Pack of 3)
Great value and product was ready to use and worked instantly.
Reviewed in the United States on July 27, 2026 by Amazon Customer

Works good at a fair price
Size: 12 oz (Pack of 1)
Granulated powder perfect for my hot tub. Works good and a fair price.
Reviewed in the United States on July 11, 2026 by bnj

Soft water cure
Size: 12 oz (Pack of 1)
Have to use this every time I change the water in our hot tub. Works well!
Reviewed in the United States on July 8, 2026 by Lyle Hanks

Easy to add.
Size: 12 oz (Pack of 1)
Easy to add and calculate based on the hardness scale on the bottle.
Reviewed in the United States on May 3, 2026 by Justin Fitzpatrick

Works great
Size: 12 oz (Pack of 1)
This works as well as any product you would buy at a pool supply
Reviewed in the United States on July 7, 2026 by oopcie

prompt delivery
Size: 12 oz (Pack of 3)
Prompt delivery. Reasonable price.
Reviewed in the United States on July 26, 2026 by Daniel Voetmann

👍
Size: 12 oz (Pack of 1)
Excellent quality and service thank you 👍
Reviewed in the United States on October 22, 2026 by Russell Motta

Good item
Size: 12 oz (Pack of 1)
Good product
Reviewed in the United States on October 18, 2026 by Micah D
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