Part 2: How Aquaponics Works In Spite of Everything

by Scott Beuerlein, Horticulturist

How It Works

So before we go into the “lessons learned,” which will be our final installment, here is a quick briefing on how aquaponics works. Aquaponics is a closed loop agricultural system in which fish are raised in a tank. Water from the fish tank is continuously pumped up to a bio-reactor, which is a fancy word for a small filtration system that mainly houses bacteria; that bacteria converts ammonia from the fish waste into forms of nutrients for plants; water exits the bio-reactor and is dispersed through trays housing plants, which take up the nutrients. The water then falls back into the fish tanks so clean that it makes for happy, healthy, hungry fish. We feed the fish and thereby keep the whole cycle going.

One of the 200 gallon fish tanks in the Aquaponics Greenhouse.

Our system is in a small, 12’ x 25’ greenhouse divided into two sides of two trays each. One side consists of a tray with hydroton, which is expanded clay balls, ($300.00, available from hydroponic suppliers), the other tray is a raft bed, made from foam insulation that floats on the water. Plants are stuck into 1” holes in the foam so their roots hang in the water. The other side is the same, except we substituted ordinary limestone gravel ($15.00) for the hydroton. Air is pumped into the fish tank, the bio-reactor, and the raft tanks. The only inputs are fish food, small amounts of a few nutrients, organic pest controls like insecticidal soap (used sparingly), electricity for the pumps, gas for the heating system, and water.

Happy plants in the grow beds of the aquaponics system.

Why It Works

As a horticulturist who has studied roots and soil and how air and water and nutrients all work together to make plants grow, I still consider aquaponics a weird kind of alchemy. I cannot wrap my head around the idea that roots, which would rot at the drop of a hat in wet, mucky soil, can thrive in a tank of water. Sure, I know there’s plenty of oxygen in that water, and, true, without soil there are no soil-borne pathogens in the system, but, still, sorcery of some kind or other must be at play!  But that kind of thing has never bothered me very much—could never understand why Darren held onto his ideals with such a blind death grip on Bewitched and didn’t just go with the flow. Seriously, a twitch of the nose and you’re living the dream on the French Riviera? Fool! He caused so much stress in their lives. Anyway, fact is, aquaponics works and it works pretty darned good.

In our next and final episode, we’ll reveal the “Lessons We Learned”, which, although fulfilling, will leaving you wanting more.

Contributors: Linda Castaneda, & Wendy Rice

Tom Tenhundfeld works as a keeper at the Cincinnati Zoo’s off-site breeding facility, Mast Farm. Tom lives and works at the Mast Farm where he is responsible for the daily maintenance and upkeep of the huge 107-acre property as well as the care and husbandry of breeding populations of cranes and cheetahs, among other species.

Tom Tenhundfeld and Cathryn Hilker

Speaking of cheetahs, Tom is the leader of one of the most consistently successful cheetah breeding programs in the country. Since 2002, 41 cheetah cubs have been produced at the facility under Tom’s guidance. He is patient, but tenacious with his collection, and his attention to detail and knowledge of cheetah language is a skill that is unique and that no doubt contributes to his success.

Tom used to be an on-grounds hoofed stock and carnivore keeper. His animal sense and years of experience make him invaluable in his current role. He always puts his animals first and isn’t afraid to speak on behalf of their well-being. We are proud to have Tom on our team!

By Guest Blogger, Scott Beuerlein, Horticulturist

I have to admit, I took on the aquaponics project with some trepidation. Years back, I had flirted a little with permaculture. On ¾ of an acre of prime Anderson Township suburbia, my wife and I had made a valiant stab at going off the grid. Between a large organic vegetable garden, a mini-orchard, a wood burning stove,  wine-making, maple sugaring, and more, our little homestead of a pair of parents, kids, border collies, cars, and jobs, we made a fairly good go of being self-sufficient. It was a challenge. It was fun. Most of all, it was exhausting. I eventually burned out. We moved on. My restless mind drifted on to other things. Yet, in moments of weakness and nostalgia, I sometimes found myself pining for a more difficult life—the kind that only sustainable home agriculture can provide. Inexplicably, despite knowing what I knew, I was ready for a new challenge. Maybe this was a weird new twist on the old mid-life crisis? So when the aquaponics project presented itself, I was tempted. Really tempted.  But one more thing gave me yet more pause. There were rumors around that all the Zoo higher ups, and all but three of the Zoo lower downs, had what was reported as delusional expectations for this thing. As a consequence, lying awake at night in a cold sweat and thinking about it, the specter of failure loomed large not only as an option, but as a likely and spectacular one. But in the end, with all this in mind, and fully aware that I didn’t have enough time to take this on; I did what I always do and proceeded anyway.

The fellas that helped get the aquaponics system started at the Zoo.

First thing, I sought out experienced, wizened old hands who had been there and done that—the stereotypical weather worn, decrepit souls who had seen it all over many hard years and would recount their pearls of wisdom in anachronistically worded , enigmatic fables, riddles, and parables.  But I quickly learned that no such people exist. Aquaponics is too new. Way too new. The wizened old hands are usually kids who left Americorps two months ago. They smile with cherubic faces, spew enthusiasm, contain not a fiber of cynicism, couldn’t embellish a story to save their lives, and sport names like Josh or Skippy. Moreover, when they recall anything, it always begins with, “Last year…”. The most common phrase in aquaponics circles is: “I was wondering that too.”The second is: “Chad’s parents are out of town. We’re having a party!” It’s not much of an exaggeration to state that everyone is making this up as they go along.  Eventually, I did fall in with a pack of aquaponics geeks who were starting a system along with people from Cincinnati Parks for a Krohn Conservatory exhibit. This group, absurdly old for this sort of thing, consisted of Pete West, a retired engineer who was starting a sustainable agriculture company called Self-Sustaining Enterprises; Designer and Landscaper Adam Wyman of Elements Pro. Kevin Savage, a science teacher from Cincinnati Hills Christian Academy:  and Dan Divelbiss, Chief Growing Officer and Founder of Waterfields, LLC, a company growing hydroponic vegetables in Price Hill.  Tracy Fryburger from Cincinnati Parks also generously gave advice and encouragement.

The tremendous help these folks provided simply cannot be over stated. They helped with everything from sourcing of equipment and supplies to testing the waters (literally). They came early. They came often. They returned all my calls, answered my questions , and never charged a dime. These were all genius level guys who showed up with laptops, expensive hand held meters, thick catalogs, thicker glasses, mysterious texts, a buzz word rapport amongst each other, inside jokes, and degrees like “Engineering.” I could’ve been intimidated, but I wasn’t.  My Dad is a genius level engineer of that ilk, and I’ve been smarter than him ever since I can remember. Sure, unlike me, these guys could calculate themselves out of a paper bag, but can they think like a fish? Or a plant? I can. That’s my genius. Ultimately, it turned out those genius guys’ abilities to read technical texts and do math combined with my knowledge and skills from a long, varied, and checkered past walking all manner of plants through the valley of the shadow of death made for a pretty darn good team.

In house, credit must be also given to the Zoo’s crack maintenance staff. Need a bench to put 300 pound tanks of water onto? Give Terry Jackson 4 ½ hours and a pile of stainless steel scrap  and he will build one that will last a thousand years. From our Aquatics Department, David Wardlow knows literally everything. It might take a day or two to find him, because he is in so much demand, but track him down, drop your problem on him, give him a minute or two to ruminate, and, bang, out comes a great solution.  He answered my entire myriad of weird, little pump, filtration, and plumbing questions with surprisingly little cussing. Fia Cifuentes from our Sustainability Program, folks in the Animal Department, and many others also provided support. I’m ashamed to admit that it came as something of a surprise that the Zoo is a ridiculous embarrassment of riches if you’re trying to do something that involves plants, animals, and water. Finally, special recognition must go to all those smiling, alluring, beautiful sirens (and Chad) from our PR Department who pounced upon me one day while I was quietly eating at the café and against every last bit of my better judgment talked me into doing an aquaponics rap video. Pat Story, our video sorcerer, then managed to turn what I was certain was the most unusable footage in video history from a pile of vile into something that almost went viral.

Credit also goes to Chef Brian McCorkell from the Base Camp Café. Since he is always here and never leaves, he took on the role of feeding the fish and checking on the system on a daily basis. Things have gone a lot better and smoother under his ever steady hand.

Chef Brian harvesting basil for the Base Camp Cafe.

Last but certainly not least, none of this would have been possible were it not for the generosity of The Woodward Family Charity Foundation, which funded the greenhouse and equipment. The Cincinnati Zoo & Botanical Garden is incredibly grateful to them, as are our many guests! One of the most rewarding things about this system has been the high level of interest shown by visitors, and the aquaponics greenhouse has become a popular stop on our ever expanding list of visitor engagement opportunities.

Stay tuned for two more exciting episodes in the near future. You’ll find the next installment, “How It Works In Spite of Everything” especially riveting, and the final chapter “Lessons We Learned” will make you laugh, cry, and build your own system!