Ben and Rebecca Frimmer take the concept of "farm to table" literally. Before moving to their current home in the Wissahickon neighborhood, the organic farming enthusiasts set up a hydroponic growing system in their apartment, and then, with a few ornamental koi fish, began to experiment with aquaponics.

"Once our entire dining room became basically a small farm," they knew it was time to move, says Rebecca.

In 2012, they launched Frimmer Family Farms, joining the blossoming urban micro-farm movement and producing a variety of leafy organic veggies for local venues including Weavers Way Co-op. When they decided to try aquaponics, Ben (who developed his green thumb on an Israeli kibbutz) did a custom retrofit of their original nutrient film technique (NFT) hydroponic system, which set plants in rows with narrow channels of water running past the roots.

Traditionally, roots draw dissolved nutrients from water in the soil. Hydroponics does away with the soil in favor of a fertilized nutrient solution cycling throughout the system. 

Aquaponics is a combination of hydroponics and aquaculture (raising animals like fish or shellfish). With aquaponics, water cycles between plants and a tank of fish — their waste products nourish the plants naturally. There are various aquaponic set-ups, including NFT, a system of floating plant rafts, or a media bed (like gravel) that is periodically flooded and drained.

In each case, a series of tanks or tubs, plant beds, tubes and pumps keeps everything flowing. A filter between the fish tank and the plants' roots is populated with helpful bacteria, converting the fishes' waste into nitrates for the plants. The water is filtered clean by the plants, then returned to the fish. This high-efficiency system produces both animal protein and organic vegetables in a limited footprint, giving it high potential for urban farmers looking to diversify their businesses.

Instead of pouring water into the ground, imagine "turning on your hose and capturing that water and putting it back in your tap," says Aaron Flora, California-based founder and CEO of Renewable Farms, an organization that helped to launch a small volunteer-run aquaponics system on the site of a burned-out Kensington building in 2011.

In a world of dwindling water supplies, that efficiency becomes a major draw for aquaponics. Another is the production of animal protein in the same low-impact system; the fish are harvested along with the crops.

Dr. Steven Hughes, aquaculture specialist and associate professor of biology at Chester County's Cheyney University (about twenty miles west of Philadelphia), explains that misconceptions about farming in general can lead to an unfortunate knee-jerk reaction to aquaponics. 

With rampant "horror stories" about animals raised on antibiotic and chemical cocktails, many people have the mentality, "farm-raised, it's got to be bad," says Hughes. "And it's not." 

As the originator and director of Cheyney's Aquaculture Research and Education Center (AREC), Hughes says it's all about the type of system you use, and it's hard to beat organic aquaponics for healthy, fresh, locally-sourced vegetables and protein. 

At AREC, the school partners with Chester County-based Herban Farms, whose aquaponic greenhouse sits on campus. The organic basil belongs to Herban Farms, which sells the herb throughout Chester and Delaware counties. The tilapia in the tanks belong to the university, and the school and the farm work hand-in-hand on research to improve the system.

That's because aquaponics isn't easy to master. In fact, Ben and Rebecca encountered so many challenges that they decided to halt their aquaponics outfit (their koi fish, which were never destined for dinner, went to a happy home in a pond). 

"I found that aquaponics was all the problems of hydroponics combined with all the problems of aquaculture as well as the problems of running a farm," says Ben. Managing day jobs as well as the farm at home, the couple found that handling the filters, pH and nutrient fluctuations was a big job.

"In the end, we gave it up because you don't feel like a farmer anymore. You feel like a plumber," adds Ben. There was always a leak, a balky siphon or a clogged filter. Without a fully-automated, climate-controlled greenhouse or a full-time staff, the project wasn't a feasible way for them to produce store-worthy yields in their 20-by-12 foot backyard space. 

"We really made a decision that we wanted to get our hands in the dirt again," explains Rebecca, noting that their commitment to a totally organic, non-GMO product meant shipping special fish food in from Florida, an expensive proposition. 

The couple does tout a seasonal, media-bed aquaponics system for families interested in growing their own food. 

"For a backyard model, to add food security to your house, I think aquaponics is incredible and I highly recommend it to everyone," says Ben. But for "commercial farming large-scale to feed a nation, I really don't see [aquaponics] happening."

Bob Kilgore, founder of Brogue Hydroponics, whose produce appears at Philadelphia's year-round Fitler Square Farmers' Market, disagrees.

Aquaponics on a large scale "is fully possible and profitable, but it has to be done right," he says. Farmers have to pay special attention to capital expenses and the marketability of the products. Will Allen, sustainability and urban farming pioneer, has had tremendous success with aquaponics at his organization Growing Power in Milwaukee, Wisconsin.

Located near Lancaster, Kilgore had his first hydroponic harvest in 1984, and recently began to branch out into aquaponics, successfully growing a variety of herbs with the help of goldfish, catfish, perch, bass and trout. 

Unlike Kilgore's veggies, his fish aren't available on the Philly market yet, but he says that's a major goal for early 2014. In the meantime, his trout have made their way to restaurants in York, Lancaster and Harrisburg. 

"I love the idea just because it's so sustainable: the cycle of taking the fish waste and using that to grow the plants," he says. "We spend a little bit less for fish food than we spend for hydroponic fertilizer, and then on top of that you get the benefit of fresh fish."  

But like Hughes and the Frimmers, Kilgore acknowledges that aquaponics is a long-term investment with many challenges. For example, treatments for any sick fish may render the crops inedible, or vice versa. Kilgore recommends a modular system that keeps a problem in one tank or bed from affecting the others. 

Every aquaponics enthusiast touts different benefits. Flora's Renewable Farms works across the country to help "intentional communities" launch sustainable, locally-led projects, and the Kensington aquaponics site (created with the help of Allegheny-based nonprofit The Simple Way) means more than eco-friendly nutrition for a handful of people.

"I use aquaponics as a tool to empower people," says Flora. "The main goal is to try to provide jobs and dignity, not just fish farms."

Hughes believes aquaponics is vital to the future.

By 2020, "we're going to need roughly twice as much food as we are producing right now," he says. "We're not going to produce [it] by traditional agriculture. We don't have the land, or the productivity." 

From backyard growers to schools to professional farms in Philadelphia and beyond, aquaponics is gaining ground. Kilgore says that when he started with hydroponics, not many people were doing it. But "as more and more people got into it, the whole science evolved." It looks like the urban-friendly technology of aquaponics is ready to do the same. 

ALAINA MABASO, a Philadelphia-based freelance journalist, has landed squarely in what people tell her is the worst possible career of the twenty-first century. So she makes Pennsylvania her classroom, covering everything from business to theater to toad migrations. After her editors go to bed, she blogs at http://alainamabaso.wordpress.com/. Find her on Twitter @AlainaMabaso.