Lesson 5: Testing Hardness

Calcium hardness is the total mineral content of the water. If there is too much hardness, the water will become saturated and the minerals will deposit on any surface inside the pool, like the ladders or lights. If there is too little hardness, the water will corrode any surface inside the pool that has calcium. Can you test the water hardness?

Doing the science

1. Start the Pool Bacteria Simulation by clicking on the "Sim" tab.
2. Click on the "Hardness" checkbox on the section labeled "Tests" and adjust the "Number of Swimmers" to 5.
3. Click on the "Run" button.
4. Click on 0, 6, and 12 under "Time (hours)" to find the hardness level at that time period. Record the hardness level in Table 1 below.
5. Hover over the children to see their reactions to swimming in the pool. Record some of their comments in the table.
6. Click on the "Reset" button.
7. Repeat steps 2-6 with the number of swimmers designated in Table 1.