By Natural Chemistry



Model # 04105

Alternate Part #'s NC04105EACH

Product Description

Natural Chemistry Calcium Hardness Increaser 1.75lbs. - Bring your calcium into ideal range

Spa Calcium Hardness Increaser improves bather comfort by bringing calcium hardness into ideal range. It is part of the Adjust group of products used in the Spa EASE program.


  • Protects spa surfaces and equipment
  • Easy to dose & measure cap


  • All values are in dry ounces
     Spa Volume  20ppm 40ppm  80ppm   100ppm
     200gal  1oz  1 1/2oz  3 1/4oz  4 1/4oz
     400gal  1 1/2oz  3 1/4oz  6 1/2oz  8oz
     800gal  3oz  6 1/2oz  13oz  16oz
    Note: NCI threaded safety cap= 1/2oz of this product NCI large overcap= 4oz of this product

How to Apply:

  1. Test spa water for calcium hardness level
  2. Compare test results to chart (above) to determine appropriate amount of Natural Chemistry's Spa Calcium Hardness Increaser necessary to make adjustment
  3. With spa circulating pump on high speed, add required amount directly to spa water
  4. Continue circulating water a minimum of 20 minutes
  5. Re-test and adjust if necessary * Do not pre-dissolve this treatment as heat is generated when it contacts water*

Features & Benefits:

  • Brings calcium hardness level to ideal range
  • Reduces cloudy water caused by low calcium levels

For our complete line of Natural Chemistry Pool & Spa Chemicals

Product Specifications

1.75 lbs.

?     Asked on 11/30/2012by Guest

What is Calcium Hardness? Do I need it?

A  Answered on 11/30/2012 by InyoPools Product Specialist Patrick P.

Calcium Hardness is the calcium content of the water. If the calcium hardness is too low, the water becomes corrosive and results in the etching of the pool's surface. If the calcium hardness is too high, the result will be scale formation on all pool surfaces.

?     Asked on 5/20/2020by Peter Sullivan

recommended calcium hardness is 200-400ppm. mine is 90. how do I correct?

A  Answered on 5/20/2020 by InyoPools Product Specialist Patrick P.

Peter this is the product you will need.


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