Education

Which pool covers are best at saving water? Cal Poly aims to find out

Lee Valenzuela, a board member with the National Plasterers Council, walks past one of several pools at Cal Poly that are being used in a study to determine the effectiveness of pool covers in reducing evaporation.
Lee Valenzuela, a board member with the National Plasterers Council, walks past one of several pools at Cal Poly that are being used in a study to determine the effectiveness of pool covers in reducing evaporation. jjohnston@thetribunenews.com

On toasty summer days, jumping in a pool can be a refreshing way to cool off.

But with an emphasis on water conservation during the drought, many people may be missing out on an easy way to save water — using a pool cover.

Cal Poly is testing a variety of pool covers and liquid chemical additives to see which are most effective in helping pool owners reduce evaporation and conserve water.

The study is being conducted at Cal Poly’s National Pool Industry Research Center located on campus near Baggett Stadium.

“Our goal is to provide the industry and consumers with the best information about what pool covers offer the best protection from evaporation,” said Alan Smith, research chairman for the National Plasterers Council, a nonprofit trade association collaborating with Cal Poly on the study. “We know that most people don’t use pool covers (or liquid chemicals) at all. If people used them across the state, it could save a significant amount of water.”

The council estimates that by using pool covers or nontoxic, alcohol-based liquid chemicals, California can save an average of 30 percent of pool water lost through evaporation — an estimated 10,833 acre-feet or 3.5 billion gallons per year.

The lead researcher is Misgana Muleta, an associate professor of civil and environmental engineering at Cal Poly, with the assistance of graduate student Ernesto Jimenez.

The study will examine different covers used in pools separated by concrete dividers in Cal Poly’s test center — which is closed off to public use for swimming.

Those coverings include solid track covers (likely to show the least amount of evaporation), a foam cover, blanket cover, bubble cover and solar rings, as well as liquid chemicals.

Different covers may be more effective for different pool shapes and sizes.

“If you have a weird, amoeba-shaped pool and you can’t get a track cover on it, what’s the next best thing in the market-available covers to help save that water?” Smith said. “This will be able to tell you, in order, comparative to each one. It will be good data for everybody to use.”

Muleta said the process for studying the evaporation is simple. The testing will take place over 60 days, starting this week, and Jimenez and he will use rulers attached to the sidewalls of each pool to measure and compare the dropping water levels.

“We expect to release our results within a couple of weeks from the conclusion of the study,” Muleta said. “We also plan to publish in a science magazine.”

The National Plasterers Council has raised $4.3 million for Cal Poly’s research center, which has tested the finish used for pool surfaces in the past.

The center hasn’t been used for research since 2008 because of a declining economy and lack of funds around that time, according to Cal Poly officials.

“I’m happy to see the center finally up and running again with the use for the project,” Larson said. “This is a project that will have results that can be quickly translated for use in society.”

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