Here we see Bill installing the “Filtration Skid” @ PR Harris Community College in Southeast Washington, DC.
This pic is from last Fall. Hey, gotta blog sumthin’…
The Filtration Skid is akin to the organs and nervous system of an advanced aquaponic system. On the Filtration Skid are a drum filter, bag filter, bio-filter, UV sterilization lights, oxygenation devices, and various pumps and sensors.
Here are Julie, Hala, and Cheryl getting ready to brew some vermicompost tea at our aquaponics meetup last night. Cheryl looks to be digging under a bed of newspaper to find our squiggly friends below.
About 10 or 15 local aquaponics enthusiasts came by to participate last night. We tested the system water for pH, ammonia, and nitrates and discussed the results; we chatted about fish feeding ratios; we brewed vermicompost tea and discussed applications for aquaponic systems; and we added worms to the media bed.
Thanks everybody who came out to visit and share your knowledge. We’ll be posting more practical info about vermicompost tea applications in aquaponics, stay tuned!
Scott has been running this system in his backyard in NE DC for over two years. Below is the fishtank, a submerged IBC Tote with cover. Scott estimates he has about 10 Bullhead Catfish and over 50 Blue Gill, some of which have been here almost three years! He and his family have eaten about 15 of their own fish grown in their own DC backyard… Gnarly! (He says the Blue Gill are much tastier.)
Up top is the grow bed. Scott estimates that during the warmer months it produces about a salad a day for his family. Wow, great numbers. And he uses rainwater from his roof, very environmentally friendly! (and lower pH)
As pictured, the system is operating under the tarp for winter. It expands out during the rest of the year, and Scott is continually adding growbeds.
Here’s a link to his forum thread in case you are interested in more info: Scott’s aquaponic forum thread.
In this pic, we see a comparison of the chlorine level between DC tap water and from an aquaponic system with the same source water. Five months ago this 30-gallon aquaponic system was treated with a small bottlecap-full of a solution to remove chloramine (“total chlorine”). Despite frequent top-offs from the same tap, there is still no chloramine detected in the aquaponic system, whereas the tapwater has 3ppm.
Municipalities add chlorine and sometimes chloramine to disinfect public drinking water. The DC Water website states: “The drinking water delivered by DC Water contains chloramines.”
Chlorine (“free chlorine”) will off-gas and dissipate naturally. But chloramine (“total chlorine”) needs to be actively removed.
Unfortunately, the same chlorine and chloramine that keeps our drinking water safe can kill our aquaponic “biofilter”: the large bacterial colony that converts fish waste into plantfood. So check with your municipality and address your chloramines if necessary so you dont kill your bacteria and your fish don’t choke on their own toxic ammonia. 🙂
Jimbo is pushing the limits of personal food production — his system can grow about six-hundred heads of lettuce at a time in his own backyard! He uses a 300 gallon IBC Tote as his fish tank, and two 20 x 4 grow troughs for his plants.
Our country relies on a wasteful and inefficient food system that contributes to pollution, resource depletion, income inequality, and poor health. Jimbo shows how we can use aquaponics and permaculture methods to produce more of our own food on our own terms!
Visit the Tomahawk Permaculture website for more info.
Let’s make 2017 a big year for aquaponics in Washington, DC! Check out what we’re up to:
Here is Niraj, Founder and Director of Cultivate the City, in one of his new rooftop greenhouses near H Street in Northeast DC.
And, in the bucket to the back left is the winter home of our goldfish from the JO Wilson aquaponic system. The fish will be fertilizing this vertical tower of strawberries. We even brought over some of the “bio-balls” from the JO Wilson biofilter to ensure an adequate bacterial colony to convert the fish waste into plant food.
Here are some decent roots on our young aquaponic kale at J.O. Wilson Elementary School, but roots ain’t gonna pay no bills! (unless they are root vegetables.)
Unfortunately we got this system, “The Cardinal”, started late in the year. We only added about 10 goldfish to start and we weren’t able to pump out any significant veggie volume. (But we did conduct numerous science lessons with students.)
We shut The Cardinal down for the Winter to protect it from the weather. (The goldfish are staying warm with Cultivate the City in a mini aquaponic system growing strawberries in a rooftop greenhouse.)
2017 will be about maximizing the production of high-quality crops, quantifying our production, and standardizing operating procedures.
In an aquaponic system your plants are ultimately eating fish food, the fish are just the middle man. Therefore, its helpful to know how much your fish weigh to calculate how much they are eating and how much plant growth they can support.
The key ratio of an aquaponics system is fish food to plant grow space. Leafy green plants will require between about 20 and 50 grams of fish food per day per square meter of grow space (assuming a fully utilized space). Fruiting plants like tomatoes and cucumbers will require a higher ratio between 50–80 grams per meter squared per day. (Somerville, et al 2014)
Once you figure out how much fish food your plants require, you work backwards to figure out how much fish you need. And this is based on a standard fish diet of about 2% of their body weight per day.
If you are adding too much fish food then your water quality can decrease as surplus nutrients build in the system and there’s not enough plants to filter the water. Conversely, not enough fish food and your plants won’t have enough nutrition. So know your fish weight!