Urban Organics worker Lee Scoggins flicked a cup of powder into a large blue pool and watched as 50,000 tiny salmon, each the size of a paper clip, darted toward dinner inside the newly converted old Schmidt Brewery plant in St. Paul.

The 8-week-old fish that will grow into 10-pound beauties over the next year were introduced to an enthusiastic crowd Thursday as part of the grand opening of Urban Organics’ and Pentair’s second indoor fish and produce farm, one of the largest commercial aquaponics facilities in the world.

Waste produced by 150,000 fish will help fertilize produce grown on aqua beds on the other side of the facility. The estimated $12 million project — certified as an organic farm by the U.S. Department of Agriculture — boasts 87,000 square feet and is 10 times larger than Urban Organics’ and Pentair’s first facility, which opened in the converted Hamm’s brewery in St. Paul in 2014.

“It’s a very exciting time for us,” Dave Haider, who founded Urban Organics with his wife, Kristen, and Fred Haberman and Chris Ames, told the crowd at the opening. “Six years ago, my wife said, ‘You know. We should open a [aquaponics] farm. We could do that.’ ”

The key was an unlikely pairing with Pentair, a $5 billion Wall Street stronghold, that almost didn’t happen.

“At first, [Haider] wouldn’t return my calls,” said Bob Miller, chief financial officer of Pentair’s aquatic water system business.

These 8-week-old fish will grow to 10 pounds over the next year. They had their debut on Thursday to an enthusiastic crowd.

Haider sheepishly smiled. “It’s true,” he said.

Then Miller emphasized in a voice message that Pentair is a filtration expert that could probably help the tiny Urban Organics company with a host of equipment and engineering solutions. Pentair also wanted to prove fish and produce aquaponics farms are viable commercial concerns that can solve food shortage problems, Miller said.

With an added boost from the city of St. Paul, the partners were on their way to creating their new business.

The partnership works, Miller said, because both entities are committed to finding farming techniques that use less water and energy, and protein that is free of antibiotics and pesticides.

Urban Organics will use Pentair’s advanced pumps, filters, aerators, mineralization systems and more at the Schmidt site to raise 275,000 pounds of Atlantic salmon and arctic char fish each year. About 475,000 pounds of organic greens including kale, bok choy and arugula also will be produced. The new operation should be at full capacity next year.

The new facility broadens Urban Organics’ product offerings. The existing tiny Hamm’s building raises striped bass and tilapia and grows basil, kale, watercress and Swiss chard.

With the two facilities, Urban Organics will serve customers across the Midwest, including the Fish Guys, Hy-Vee, Lunds & Byerlys and Co-Op Partners Warehouse in St. Paul.

“We are very excited about this partnership ... and have heard a lot of great feedback from both our patients and employees,” said Ted ­Wegleitner, president and CEO of HealthPartners’ Lakeview Health System in ­Stillwater.

Tracy Singleton, owner of the 22-year-old Birchwood Cafe, said she was “thrilled” to hear about Urban Organics.

“It’s been hard to find fish that fits our parameters for sustainable ingredients” that are free of antibiotic, mercury, PCB and overfishing concerns, she said.

Haider and co-founder Ames said their method uses 2 percent of the water usually consumed by traditional ­agriculture.

“Our local market will get the benefit of our fish and greens, but there will also be a worldwide benefit as we continue to learn from this model and apply its lessons to other locations in the future,” Haider said.