By Stephen London

Most people know that chlorine helps keep pools clean, but there is much more to the process of making pools swimmable.

In Baltimore's backyard, LifeBridge Health & Fitness' Shawn Van Oudenaren has the job of managing the aquatic center, featuring a 25-yard, five-lane lap, 95,000-gallon pool and a 10,000-gallon therapy pool. Lifeguards check the chlorine levels, but Van Oudenaren takes other measurements and checks the chemical balances.

Pool owners must maintain three major chemical balances in order for  pools to be usable. The pH balance, the alkalinity hardness and the calcium hardness affect one another, so it takes numerous tries to achieve the perfect equilibrium. LifeBridge has a saltwater pool, which introduces a couple tests that would not normally be tested on regular, freshwater pools.

"A big misconception for a lot of people is that saltwater pools have no chlorine," Van Oudenaren said. "A saltwater pool naturally produces the chlorine. The only thing the health department checks is the chlorine and pH. But we check everything, even phosphates, because it is a saltwater pool."

A good pH level for a pool ranges between 7.2 and 7.6 on the pH scale. The alkalinity hardness is testing the total alkalinity, or weak acids, in the water. A pool's alkalinity hardness should measure anywhere between 80 to 150 parts per million.

Calcium hardness refers to the actual hardness of the water. The harder the water, the higher the calcium levels and vice versa. The calcium hardness should be in the range of 200-400 parts per million. It is recommended to check calcium hardness once every week, but LifeBridge employees check it 2-3 times per week.

Roughly 200 people use the LifeBridge pool each day, which is why it has to be so rigorously tested. Phosphates are tested because the salt in the pool can raise levels of phosphates, and the LifeBridge team also has to test the total dissolved solids. Saltwater pools may require extra maintenance, but they also make a difference to the swimmers, Van Oudenaren said.

"People always comment to me how much they love the saltwater pool," he said.

Issue 174: June 2012