Rooting DC Conference

Here are some Cultivate the City rascals, with whom we shared a table at the 2017 Rooting DC Conference last Saturday.

Rooting DC is an annual forum for urban ag folks looking to make DC’s food system healthier. Click to see Rooting DC’s great map of the DC Food System… Hey, we gotta put some aquaponic systems on that map!

Anacostia Aquaponics gave a short “intro to aquaponics” presentation. We also ran into a lot of old friends, and made some new ones. It’s likely that Rooting DC pollinated even more urban agriculture collaborations, stay tuned!   🙂

Checkout Scott’s Backyard System in NE DC!

scotts system

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.


So What’s the Deal With Chlorine?


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’s Backyard System in Northern Virginia

Jimbo's System

Check out Jimbo’s backyard aquaponic system in Northern Virginia.

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.



Home for the Winter

Home for the Winter

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.

Room for Improvement…

Room For Improvement...

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.

Quantifying and Monetizing the Benefits of Aquaponics

Quantifying and Monetizing the Benefits of Aquaponics

You see, in our economic system we don’t account for the hidden costs of food production. Aquaponic producers have difficulty monetizing their benefits because industrial agriculture producers have an implicit subsidy to use as much water, carbon, pesticides, fertilizers, and antibiotics they want! Even a conservative economist should support public actions to force producers to internalize these costs of production so that others don’t have to pay later.

Click the link below to check out a PDF presentation by Anacostia Aquaponics Director Brian Filipowich on this topic. It was given at the Aquaponics Association conference in Austin, TX this past November.

Quantifying and Monetizing the Benefits of Aquaponics

Know Your Fish Weight

Fish Weight

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!