Service professional Javier Payan was facing a problem that didn’t seem to have a solution.
A client had been complaining about discoloration on his glass-bead-finish pool. It was occurring on a shallow step. Payan looked at the pool but didn’t think it was a big deal: He figured the mauve-like tone was the result of some minor discoloration. He didn’t understand his client’s anxiety.
“Then they said, ‘No, no, this used to be blue,’” says Payan, president of Payan Pool Service in El Cajon, Calif.
The exposed aggregate kept the discoloration from looking too drastic. But when you looked up close, you could see that the cement binding the beads was a brick red.
Payan tried acid, he brought colleagues to look at it — all to no avail. He asked if the homeowner could live with it. No way, the customer said, he was a perfectionist and it was driving him crazy. If he had to replace the finish at the estimated $18,000, so be it.
In the hopes of avoiding such a drastic measure, Payan called in Greg Garrett, director of technical services for the National Plasterers Council and owner of Applied Materials Technology in Chandler, Ariz. He scratched the surface of the material with a dental pick and found blue underneath. He noted that the pool was sanitized with ozone and a salt chlorine generator, and that a nearby spillway generated significant volumes.
After some research, Garrett found that a red cobalt mineral exists in nature, called spherocobaltite. As it turns out, the nearby spillway was oxygenating the water, driving off carbon dioxide. That, in concert with the ozone and salt system, drove up the pH, causing the surface reaction.
Garrett suggested performing a zero-alkalinity process on the pool, which would require administering about 10 gallons of acid into the pool and holding it for seven days. Payan warned the homeowner about the risks and had him sign a liability waiver.
After a few days of doing the process and monitoring the pool, the red was gone. To manage the issue, Payan plans to install an ORP/pH controller.
“They thought either there was something defective in the material or that Javier and his company were doing something wrong,” Garrett says. “But, no, this was a perfect storm of events that created color change in the surface.”
