PARADISE ISLAND, Bahamas On a sun-drenched weekend in September, a group of South Florida charter school principals jetted off to a leadership retreat at The Cove, an exclusive enclave of the Atlantis resort. A Friday morning meeting gave way to champagne flutes, a dip in the pool and a trip down a waterslide. The evening ended at the casino.

Leading the toast by the pool: Fernando Zulueta, the CEO of Academica Corp., which manages the principals’ schools.

Zulueta had reason to cheer. During the past 15 years, Zulueta and his brother, Ignacio, have built Academica into Florida’s largest and richest for-profit charter school management company, and one of the largest in the country. In Miami-Dade and Broward counties, Academica runs more than 60 schools with $158 million in total annual revenue and more than 20,000 students — more pupils than 38 Florida school districts, records show.

Academica’s schools consistently get high marks for academic achievement, with some schools earning national recognition. Mater Academy Charter High in Hialeah Gardens is considered among the nation’s best high schools by U.S. News & World Report, and recently won the College Board Inspiration Award.

And despite recent cuts in state funding for public and charter schools, Academica’s schools have prospered financially: One of its chains of nonprofit schools has assets of more than $36 million, the company says.

Academica’s achievements have been profitable. The South Miami company receives more than $9 million a year in management fees just from its South Florida charter schools — fees that ultimately come from public tax dollars.

But the Zuluetas’ greatest financial success is largely unseen: Through more than two dozen other companies, the Zuluetas control more than $115 million in South Florida real estate — all exempt from property taxes as public schools — and act as landlords for many of Academica’s signature schools, records show.

These companies collected about $19 million in lease payments last year from charter schools — with nine schools paying rents exceeding 20 percent of their revenue, records show.

Academica has fostered a close-knit culture among its schools, recruiting principals and teachers who rarely leave the ranks and are often promoted from one Academica school to another — though the staffers technically work for their respective schools, not for the management company.

Dual roles

But the principals play another crucial role: Several also serve as board members at other Academica schools, where they approve and oversee Academica’s management contracts and the real-estate leases — including the leases with the Zulueta companies.

Zulueta says the schools and their boards are all independent and free of Academica control, and any real-estate deals with his other companies are done at arm’s length and at fair market value.

“We take our cue from what the board’s mission is,” Zulueta said. “The [school] principals don’t report to Academica.”

The big four

Academica’s reach extends from Florida to Georgia, Texas, Nevada, Utah and California, where the company also manages charter schools. But Academica is best known for managing four prominent school networks in Miami-Dade and Broward counties: the Mater Academies, the Somerset Academies, the Doral Academies and the Pinecrest Academies.