To raise the Calcium Hardness of a 28,000-gallon hotel pool from 100 ppm to 400 ppm, how much calcium chloride (77%) is needed?

To determine the amount of calcium chloride needed to raise the calcium hardness of a pool, it’s important to understand the relationship between the concentration that needs to be achieved, the volume of water in the pool, and the characteristics of the calcium chloride being used.

In this scenario, you aim to increase calcium hardness from 100 ppm to 400 ppm. This implies an increase of 300 ppm (400 – 100 = 300 ppm). To find out how much calcium chloride is required, one uses a formula that incorporates the volume of the pool and the desired change in calcium hardness.

For a pool with 28,000 gallons of water, this means you're looking to increase the overall calcium hardness in parts per million (ppm). To convert gallons to pounds, one must account for the weight of water (there are approximately 8.34 pounds per gallon). Therefore, the total weight of water in the pool is:

28,000 gallons × 8.34 lbs/gallon ≈ 233,520 lbs.

Next, you calculate how many pounds of calcium chloride are necessary to achieve a certain increase in calcium hardness per million parts:

1 ppm in 1 gallon of water is equivalent to 8.34 lbs of water, which directly translates