Maintaining Proper Calcium Levels In Your Pool

Calcium Hardness

Calcium hardness is a measure of the dissolved calcium in water. The calcium hardness level should be maintained at a minimum of 200 ppm. If it exceeds 500 ppm, then the pool water may need to be diluted. Normally, except in the western U.S., calcium hardness levels do not get too high unless the pool is using large amounts of calcium-based
chemicals like Cal Hypo chlorine granules or tablets.

There are a couple of problems that can result from having improper calcium hardness levels: 1. If the calcium hardness is too low, then the calcium starved water may leach calcium out of the plaster, causing pitting. 2. If the calcium hardness is too high, then cloudiness or scaling (crusty deposits) may result. Typically, the majority of scaling problems occur right after the pool is re-plastered and is the result of plaster dust that adheres to the surface.

Testing Calcium Hardness

Because calcium problems appear under extreme conditions, take a water sample into your pool store every four weeks for a test. If they discover problems, research solutions or bring in a professional to asses the situation. The fact is, there are too many variables and if you take bad advice or do something wrong, you can take a bad situation and make it worse!

The Calcium hardness test involves the use of three reagents for a proper reading.

1. Fill the large TAYLOR test vial to the 25 mL mark with pool water and add 20 drops of R-0010.
2. Add 5 drops of R-0011L to the sample and swirl until you see a light red.
3. Add R-0012 drop by drop, swirl the water and count the drops until the sample turns from red to blue. Multiply the number of drops by ten to get the calcium hardness reading. i.e: 30 drops = 300 ppm (disregard any pink “fl oaters” caused by magnesium hardness in the water).
4. A good Calcium hardness reading is between 200 and 500. If the calcium level is above 500 consult with your local pool professional.