Calcium Hardness Increaser – 12 fl oz, SpaGuard®

Calcium Hardness Increaser (Part #42636BIO) is a liquid formula specifically designed to increase calcium hardness levels in hot tubs and spas. Low calcium can lead to etching, surface damage, and equipment corrosion. This 12 fl oz bottle is ideal for smaller applications or maintenance adjustments.

• Size: 12 fl oz bottle

• Purpose: Increases calcium hardness to protect spa components

• Benefits:

  • Prevents corrosion and surface damage

  • Maintains ideal water balance

  • Helps reduce foam caused by water softness

  • Safe for all spa finishes and compatible with all sanitizers

• Application: Test water before use. Add with jets running. Follow label directions for dosage based on water volume and calcium levels.

Essential for maintaining a healthy spa environment in areas with soft or naturally low-calcium water.

We want you to be completely satisfied with your purchase. If for any reason you need to return an item, please review our policy below:

• Returns are accepted on unopened, unused items in their original packaging.

• Items must be returned within 30 days of purchase.

• Customers are responsible for return shipping costs.

• Once the returned item is received and inspected, a refund will be issued to the original payment method within 5–7 business days.

• Opened or used items cannot be returned.

To initiate a return, please contact us at 970-259-0468 with your order number.

All orders are processed and shipped within 2 business days via standard ground shipping.
Free local delivery is available for residents within the Durango, CO area—qualifying zip codes will automatically receive this option at checkout.
Shipping rates are calculated at checkout based on order weight.