POOL CARE BASICS: CALCIUM HARDNESS (CH)

Target Range: 200-300 ppm

What is Calcium Hardness in pools?

Calcium hardness is a concentration of calcium ions which appears in the pool water in the form of calcium carbonate. Calcium is naturally present in water, but when it comes to your swimming pool water, it needs to be maintained and prevented from going either too high or too low by keeping it within the target range of 200-300 ppm.

If Calcium Hardness is not kept within range, your pool water can become too aggressive or end up scaling the surface of your swimming pool.

In situations where the water is very soft and contains very low levels of calcium the water will become aggressive by seeking out more calcium by dissolving it from surfaces it comes into contact with that contains calcium, such as plaster, grout, and concrete decking. With vinyl pools, there is very little calcium in the structure, but over time, such aggressive water can cause the liner to lose some of its plasticity, and fail prematurely. Fiberglass pools can become etched and lose some of the gel coat gloss when Calcium Hardness levels are too low. Also known as a Corrosive water condition.

Problems Indicating Low Calcium Hardness:

  • Pitting and etching of the plaster

  • Pitting and etching of concrete surfaces

  • Dissolving of grout

  • Possible heater failure

When the pool water has a level of calcium that is too high, the excess calcium begins forming deposits on the pool's surfaces, which is referred to as carbonate scale, or simply scale which appears as a “white-ish,” crystallized rough spot.

Problems Indicating High Calcium Hardness:

  • Cloudy swimming pool water

  • Clogged filters and reduced circulation through piping

  • Heater inefficiency

  • Scaling of the pool water


Having problems balancing and maintaining your pool water? NO PROBLEM! Bring your water sample into one of our stores & let our chemical experts test it for FREE!