AquaStar Pool Products has been sued by Zodiac Pool Systems for trademark infringement.

In response, AquaStar has counter-sued.

Last fall, AquaStar began promoting a new automatic pool cleaner called StealthStar, which is still being prepared for distribution. Zodiac filed suit in February, claiming the StealthStar infringed on the appearance, known as “trade dress,” of the Polaris cleaner line, as embodied by the Polaris 280. Like the Zodiac model, the StealthStar features three wheels — two on one side, one on the other. Zodiac said the design, size and proportions of the wheels are “arbitrary and ornamental,” and trademarked by the Vista, Calif.-based plaintiff.

“Zodiac’s trade dress has become ... Zodiac’s trademark,” the company stated in court documents, adding that “The StealthStar pool products are counterfeits of the distinctive designs of Zodiac’s trade dress.”

Zodiac charged San Diego-based AquaStar with trademark infringement, trademark counterfeiting, false designation of origin and unfair competition.

Due to the alleged similarities in appearance, Zodiac said, dealers and consumers will confuse StealthStar for the Polaris models. Zodiac asked the court to award damages and impose injunctions against AquaStar to prevent it from selling StealthStar in its current design. “Zodiac has suffered and will continue to suffer irreparable injury to its rights and suffer substantial loss of goodwill and reputation unless and until AquaStar is restrained from continuing its wrongful acts ... .” the firm stated.

But AquaStar responded that the Zodiac trademarks don’t cover trade dress, which is protected indefinitely. Instead, Aquastar claims that Zodiac’s patents cover functional features, and only remain valid for 20 years. The fact that Zodiac has expired trademarks covering the design features shows that the trademarks are functional, said Zodiac’s attorney. Additionally, he said, the trademark papers stated that the three-wheel design would help the cleaner better navigate around uneven surfaces.

“Once the patents expire, then it goes into the public domain, and if you try to assert trade dress rights on those same designs, it’s kind of looked at as a back-door patent,” said Robert J. Lauson, managing partner at Lauson & Tarver, LLP, in El Segundo, Calif. “You’re trying to extend the life of your utility patent, and that’s not permissible.”

Zodiac declined to comment, citing pending litigation.

The court ruled against a temporary restraining order, stating Zodiac hadn’t met certain requirements, such as showing it would likely win the overall case or that it would suffer irreparable harm, and that the expired patents suggest the features are functional.

Lauson said Zodiac believes the suit is more a response to AquaStar’s plans to sell replacement parts for Polaris brand cleaners.

Another “Big Three” manufacturer, Hayward Pool Products, filed suit against AquaStar, citing trademark infringement, false advertising and other charges, to keep AquaStar from selling replacement parts that could be used on Hayward cleaners. The case settled.

“I think that’s a lucrative business for the manufacturers of the cleaners, and AquaStar’s trying to get into that business,” Lauson said. “And that’s really what’s causing all the friction between these companies.” The next step of the case is a settlement conference scheduled for April 26.