Pool Chemistry> Calcium Hardness:  |  Intro  Testing  |  Adjusting

Hardness – Testing

Testing Calcium Hardness

The Calcium Hardness test is a titration type of test.  It contains three elements.

First, you add the buffer solution to the sample.  In the Taylor test kit, this is done by adding 20 drops of R-0010.  

Second, you add the calcium hardness test solution to the sample.  In the Taylor test kit, this is done by adding 5 drops of R-0011.  Swirl to mix.  When the water is cold, it takes a little extra mixing to get the solution to dissolve.

Third, you add a  test reagent to the sample drop by drop, counting the number of drops until the test sample turns colors.   This is known as titrating the sample.  In the Taylor test kit, you add R-0012 drop by drop until the sample turns from blue to reddish.  Then count the number of drops of R-0012 you added and multiply by ten to get the total alkalinity reading.  In other words, if it took 25 drops, then your reading is 250 ppm.

Analyzing your Calcium Hardness Reading

It is important to keep the Calcium Hardness between 250 and 500 to help keep the plaster from scaling or pitting. 

If the calcium hardness is too low, then the calcium starved water may leach calcium out of the plaster, causing pitting.  This requires a very low calcium hardness.

If the calcium hardness is too high, then cloudiness or scaling may result.  By maintaining a slightly lower alkalinity and pH, the impact of a higher calcium hardness can be minimized.  In our experience, the majority of scaling problems occur right after the pool is replastered and is the result of plaster dust that adheres to the surface. 

If your Calcium Hardness Reading Is Too Low:

A low Calcium Hardness reading could indicate that your pool is losing a lot of water.  Typically the Calcium Hardness should stay fairly consistent in the pool, and is not lost through evaporation.  If it drops on a regular basis, it may indicate a leak in the pool.