Backyard Aquaponics in Hawaii, Grow 3000 heads of Lettuce a Month: a Profitable and Sustainable Business.
Aquaponics "No ka 'oi" means "is the best" in the Hawaiian language. "Maui no ka 'oi" has been a common saying for as long as I can remember growing up on Maui. Thus, Aquaponics no ka 'oi. Aquaponics is the best. A compact system that attempts to emulate the ecosystem found in nature to abundantly provide food for mankind. An integral part of the higher goals of permaculture and sustainability. A visitor once commented that this was like the Garden of Eden. This is the story of our attempt to create that in our backyard.
Meet the Farmers
Patty (Mom) & Larry (Pop) Yonashiro. Born in the plantation camps, and raised on Maui. Now retired. Four daughters. Five grand kids. We actually spent about 34 years away from Maui before returning in 2002 to care for our Kupuna. Larry left Maui in 1968 for a stint in the military and Vietnam, and Patty left in 1972 to finish college. Part of our time away, Larry spent working as a civilian for a Department of Defense contractor overseas. One daughter was born in Honolulu, one in Yokosuka Japan, and two were born in Okinawa. We then lived in Seattle for four years, Dillingham Alaska for ten years where Larry was the CIO and Patty the CQI nurse for an Alaska Native Tribal hospital (this is where our kids grew up and consider home), and Longmont Colorado for three years (where Larry contracted for IBM in Boulder) before returning to Hawaii on a family emergency (IBM kindly allowed Larry to work remotely in Hawaii operating a Help Desk from home for another 8 years up to 2010). Patty is a Registered Nurse (BSN, University of Hawaii) with experience in CQI (Continuous Quality Improvement) for hospital accreditation, and she also has a second degree in English Literature. Larry has a degree in business and management from the University of Maryland, up to senior level coursework in electrical engineering, and a graduate certificate in Information Systems Management from City University in Bellevue Washington. The decision to retire early was motivated in part by the desire to get as far away from our professional lives as possible, and to get back to nature. Aquaponics provided the way.
Technical Details of the Current System - Updated 06/25/14
Our system type is a Deep/Direct water culture (DWC) aquaponics system composed of five 32' x 1' deep hydroponic troughs connected in series. Each trough holds about 900 gallons of water with sixteen 2' x 4' floating rafts per trough. Each floating raft has thirty-eight 2" holes to hold 2" net pots filled with a 60/40 percent mixture of coir/vermiculite respectively, plus the seedling, giving a potential of 3,040 heads of produce in the system at any given time, at various stages of development.
Total growing space of the system is 640 square feet (ft2), calculated by 16 rafts/trough X 5 troughs = 80 rafts total. Each raft is 2' X 4' = 8 ft2 x 80 rafts = 640 ft2 total growing space. Total agricultural acreage is calculated at less than 0.1 acre including the walking areas around each trough, and the fish tank areas. Total current output of vegetables is 2,080 lbs/year at 40% production. Estimated target output at full production is 5,200 lbs/year for 0.1 acre.
Total water capacity of the system is calculated as 5 troughs x 900 gallons/trough + 3 fish tanks x 300 gallons/tank = 5,400 gallons total. Note that I also have a separate green tank (algae) to breed and hold tilapia that has about a 1700 gallon capacity. The water is recirculated, and the loss due to evapotranspiration is about 300 gallons per week (5%), replenished with city water. The system uses one MD7 Danner water pump (60 Watts continuous), which moves 300 gallons/hour up 2' to the fish tank, and then uses gravity flow to move the water through over 160 feet of trough and pipe space back to the pump. A spare MD7 is kept to quickly swap out the bad water pump for a good one. This has easily been done as a test, since the pump has not failed in 3 years.