Aquaponics, the Growing Power Way

I had the good fortune of attending a one day workshop at Growing Power in Milwaukee (AKA “mecca” for the sustainable agriculture movement) the last Thursday in October. I left Boulder the day before in a driving snow storm, but fortunately Boulder was being hit much harder than Denver and we got to Milwaukee without a hitch. As I checked into the LaQuinta Inn (trying to hide my McDonalds bag) I was preceded at the counter by a friendly young guy sporting dreadlocks. He confirmed my guess that he was a fellow Growing Power workshop attendee when an equally friendly older couple came bursting in the lobby and loudly asked if anyone was going to Growing Power tomorrow. He declared that he was (I tried harder to hide my McDonalds bag) and responded to their inquiry about the start time in the morning. He said that he had checked in with the office manager that day and was told to be there by 7:00. Yikes!

Well, it ends up that the office manager mistook the young guy for a volunteer because the four of us from the hotel were the first attendees to arrive -by a couple hours. I asked Karen Parker, the director of Growing Power, if we could be useful by helping. She declared “no, no, you are my guest. And besides, by 2:00 this afternoon you are going to be asking me for help!” followed by knowing laughter.

I wandered out of the main greenhouse, past the chickens, and over to the huge tent where a surprising number of tables and chairs were being set up for the workshop. There I discovered that they were anticipating over 200 attendees from as close as down the street to as far away as the U.S. Virgin Islands. As people started arriving I learned that their objectives were as different as their locales. Some were simply looking for an interesting way to spend the day. Some were looking for ways to help solve hunger in an impoverished African village. Some wanted to expand their current organic farm offerings to include fish. And some were seeking their next life’s work.

Finally we all took seats in the cramped tent, and Will Allen went to the podium to address the crowd. Will needed no introduction. He is a huge, muscular black man with a baseball hat and an amused smile. Despite the fact that the day was cold and drizzly he wore a sweatshirt with the sleeves cut off – his signature uniform. His arms were so massive you had the impression that cutting off the sleeves was much more about necessity and comfort than style or shirt disrepair. He took the microphone with the authority of a man on a mission, and was surrounded by his blue-shirted, mostly volunteer staff as he spoke of the work of Growing Power.

Growing Power is on a 3 acre site in an area of Milwaukee that used to be called Greenhouse Alley. As the irony of that fact sunk in, Allen continued by declaring that the area is now a “food desert”. They are 3 miles from the nearest Pick ‘n Save grocery store but only a mile from the largest low-income housing project in Milwaukee. Allen and his team use 1 of the 3 acres, 5000 pounds of worms, 10,000 pounds of food waste and 16,000 lbs of brewery waste, 25,000 pots, and the waste and flesh of thousands of fish to feed 10,000 people. This is the magic that we were all there for.

After touring the amazing complex of greenhouses, chicken coops, goat pens, and compost piles, and having a wonderful, organic lunch we were finally able to break into smaller group to learn about the specialized subjects we were most interested in. I went to the session on – you guessed it – aquaponics! The session was led by Rick Mueller and was filled with about 60 people. Below are some of the highlights

  1. Favorite plant to grow = Watercress – because it is highly nutritious, fetches a good market price, and it is the best bio-filter for the fish. They are getting 8 – 12 harvests before they need to replant. It is a succulent, so you just need to cut off a section that has roots growing out of it and plant it.
  2. Fish
    1. They have 10,000 gallons of systems growing lake perch and tilapia
      1. They heat the tilapia tanks to 85 degree, which has the side benefit of saving 50% of the cost of heating a greenhouse by running large aquaponic tanks down the middle of their greenhouses.
      2. Lake perch can handle a wide range of temperatures, so they don’t heat the perch tanks. Optimal temperature is 70, though, so it takes longer for them to grow to plate size, up to 1+ years.
  3. Biofilter philosophy – every surface in an aquaponics system is part of the bio-system
  4. Vermicomost – worms are used in every facet of growing at Growing Power, and the aquaponic systems are no exception.
    1. Cycling the system – because the plants are introduced to the system in vermicompost they can be introduced immediately (then fish after two weeks). Plus it seems to help cycle the system (worms multiply bacteria by 13x inside their bodies)
      1. In pots – salad greens are growing pots filled with 1 part compost / 1 part vermicompost / 1 part coir. The pots are set onto a shallow tray with aquaponic water running across it.
      2. Directly into the beds – watercress is grown in gravel with vermicompost spread on top, then the aquaponic water flows through the gravel.
    2. Curing nutrient deficiencies
      1. If they see yellowing they just add another dose of vermicompost or compost tea
      2. This make up for lack of fish fertilizer for the plants after a harvest
  5. Solids removal
    1. They use an aerator to keep solids suspended
    2. If the “muck gets too mucky”, they just remove it by hand. They spot check the internal temperature of the beds occasionally. If a spot is warmer than the rest of the bed it has probably gone anaerobic and the solids need to be removed. Otherwise, they don’t worry about it.
  6. Feed
    1. Live and waste products best, followed by manufactured food. They are going to experiment with raising black solider fly and are very interested in figuring out how to use worms as feed.
    2. They have duckweed growing in most beds, but Rick admits that this isn’t by design; rather “it just happens”
    3. They use trout chow as their manufactured feed.
  7. Video
    1. Here is a recent YouTube video of Will Allen explaining parts of the aquaponics setup.

That night I headed back to snowy Colorado with a 20 pound bag of worms. “What is in this bag?” asked the TSA officer. “it’s dirt, sir. Why am I carrying a bag of dirt? It has sentimental value. It comes from a place that grows plants like you wouldn’t believe”. Fortunately, they believed.

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