The GrowHaus is an indoor farm, marketplace and educational center in Denver's Elyria-Swansea neighborhood, an area considered a "food desert" lacking a grocery store within 3 square miles. Their goal is to provide healthy, affordable food for the surrounding community and raise awareness about issues of food justice and sustainability. For over a year now, Colorado Aquaponics has enjoyed a wonderful partnership with the GrowHaus.

 

Colorado Aquaponics has two different styles of aquaponic systems (profiled below) that are currently in operation at the GrowHaus. We are selling produce from these systems to the Same Cafe, a local Denver restaurant whose philosophy is that everyone, regardless of economic status, deserves the chance to eat healthy food while being treated with dignity. This philosophy aligns well with the the GrowHaus mission as well as our desire to provide environmentally and socially responsible food production.

 

Our long term intention is to design and build a large commercial scale system. We are in the process of fund raising as well as planning required to complete systems throughout the almost 20,000 s.f. reclaimed greenhouse. The development of additional systems will not only help provide food to the community and restaurants but it will also provide green jobs for the local economy and the residents of the Elyria Swansea neighborhood.

 

Below is some basic information about each of the systems designed and built by CA featured at the GrowHaus.

 

Colorado Aquaponics Bench System

 

This unique system was built with the help of grant funds committed by Kaiser Permanente. In this system we are growing a variety of seasonal vegetables like chard, broccoli and lettuce in the winter with the help of fish waste that is recirculating through the grow beds. The plants and soil-less media (lava rock, hydroton and river rock in this case) act as a natural biological filter. The plants are taking up nutrient rich water, and in turn cleaning and filtering that water before returning it back to the fish tank. Naturally occurring beneficial bacteria colonize on the surface area of all the media, as well as other surfaces, and break down ammonia (present in fish waste) into nitrites (also toxic to fish), and then finally into nitrates.

 

Water consumption is about 10% of what would be otherwise used in traditional agriculture due to the recirculating nature of the system. Plants are able to take up nutrients on a consistent basis, resulting in stronger and more rapid plant growth. The water is kept around 75 degrees, primarily for the health of Tilapia, but this also acts as a great benefit for the plants by providing warm water at the root zone. This also allows for some colder weather crops to tolerate lower average air temperatures making the system ideal for year round production.

The system functions as a flood and drain utilizing auto siphons (aka. bell siphons) that allow the beds to flood naturally to a level just below the top of the media. The automatic siphon design allows the beds to flood uniformly, providing water and nutrients to all of the plant roots. When the water reaches the top of the siphon, the beds drain rapidly and as a result the plant roots are well oxygenated. This flood and drain process happens continually in all three beds with the use of only one water pump in the whole system. The 12" deep grow beds provide an optimum depth for plant growth, vigorous root development and an effective flood and drain cycle.

 
Flood and drain systems of this nature typically follow a 1:1 or 2:1 grow bed volume to fish tank volume ratio. In this case, the three grow beds provide 450 gallons of total grow bed space compared to approximately 275 gallons of fish tank volume. This ratio is 1.6:1 which falls well within the recommended grow bed to fish tank ratio. In fact, space permitting we could easily add another grow bed or two.

 

The 275 gallon fish tank is partially sunk into the ground, allowing for the proper height for the bench top cover as well as providing additional ground insulation around the tank base. We are raising 85 Rocky Mountain White Tilapia originally from the Colorado Gator farm in Mosca, CO. There is a mixed poplulation of fingerlings and adult Tilapia.

 

This was our very first aquaponic system built for the GrowHaus with the help of many wonderful volunteers. All of the materials were donated by Colorado Aquaponics. The two tiered system design is based on the Growing Power model of aquaponics which incorporates the use of vertical farming to increase production in a limited footprint.

 

The pump located in the fish tank floods both grow beds simultaneously. The pump is on a timer which allows the pump to circulate water for 30 minutes every hour. The grow beds have a thin 2" layer of pea gravel and are slightly pitched allowing the water to drain to one end and return to the fish tank through a large tube with several slots cut into the top. This allows the water to spill out and cascade uniformly across the top of the fish tank providing additional aeration and oxygenation of the water.

 

This system is currently home to 20 rainbow trout in about 200 gallons of water. Due to the shallow nature of the grow bed medium, there is less bio-filtration available in this system therefore fish stocking densities are minimized. This helps to maintain a balanced system for good water quality parameters for the fish and adequate nutrient availability for the plants. Trout are a cold water fish and therefore prefer water temperatures ranging from 40 to 65 degrees. This tank is not  heated, saving energy and associated costs. This tank has additional aeration for the trout who require high levels of dissolved oxygen to survive.

 

In this picture, the top grow bed is growing watercress and the middle grow bed contains mostly mizuna lettuce and a few chard and other lettuce varieties.

 

 

 

 

CHOP is an acronym that stands for Constant Height One Pump. In other words, the fish tank water stays at a constant water height whereas in other designs the water level in the tank can fluctuate as the grow beds fill and drain with water. The water from the fish tank first gravity feeds into the grow bed. Once the grow bed fills, the auto siphon (described in the bench system) drains the bed into a separate sump tank. The water is then pumped up from the sump tank back into the fish tank. The fluctuations in water level take place in the sump tank rather than the fish tank.

 

This system contains 15 yellow perch who provide nutrients to a small 2x4' grow bed. This system has grown a variety of herbs, broccoli micros, watercress and lettuce varieties. We have used a single 55 gallon barrel obtained from the local Pepsi supplier for the fish tank and sump tank. Reusing materials is a great way to get started in aquaponics and save a little money as well.