“Ebb And Flow” Garden Beds

“Ebb And Flow” Garden Beds FARM HOME Miscellaneous Jason Diehl waters and feeds the plants in his gravel-filled grow beds from a fish tank on an “ebb and flow” basis Grow beds and fish tank were fabricated from 275-gal food grade plastic totes “I modeled my setup after the CHOP system developed by Murray Hallam an Australian aquaculturist ” says Diehl https://blog aquaponics net au/ CHOP stands for Constant Height One Pump Diehl uses one food-grade tote with its top cut off for a fish tank He cut 2 other totes in half and trimmed the sides to 14 in to make 3 gravel-filled grow beds with a common sump The grow beds rest on cedar boards placed on standing concrete blocks A single pump maintains a constant flow of water from the sump through flexible pipe to the 3 grow beds and the fish tank Bell siphons in the grow beds placed around the sump drain the beds into the sump about twice an hour creating the ebb and flow effect in the beds Meanwhile the constant flow into the fish tank creates an overflow into the sump “Ball valves on the flexible pipes from the sump to the grow beds restrict the flow so the beds fill to the top of the bell siphon about every 25 to 30 min ” explains Diehl The bell siphons are 7-in tall 1-in pvc pipes inside a capped 10-in tall 2-in pvc pipe Holes near the bottom of the bell allow water to fill it as the bed fills “Once the water overflows the 1-in pipe a suction is created that drains water out of the bed to the level of the holes ” says Diehl “At that point air enters breaking the siphon ” The flow bathes plant roots in nutrient-rich water from the fish tank and the ebb exposes them to air At the same time the pump floods the grow beds it is pumping water through a spray bar across the width of the fish tank It works with bubblers to oxygenate the water Overflow from the fish tank drains back into the sump via a system of hard pvc pipe Diehl used two 2-in pvc pipes that run from near the bottom of the fish tank where the fish waste settles to T-fixtures at the top of the tank One outlet open to the air prevents suction from being created Pipe on the second outlet runs over the side of the tank to merge into a single 3-in dia return pipe “I used a twin pipe overflow system to provide backup ” says Diehl “Holes drilled in caps on the ends of the pipes screen out larger particles but should one plug up the other will continue to flow ” After several years of use Diehl now has the confidence to build a more permanent system with 4 by 16-ft beds inside a 20 by 32-ft greenhouse He hopes to apply the lessons learned with his outdoor system Although designed to harvest both fish and plants Diehl found his worked well for plants but not for fish “I decided to look at them as a source of plant food ” says Diehl “I found the system was economically viable even without fish sales ” Cucumbers lettuce and other greens do particularly well as does zucchini “I harvested zucchini in half the time of soil beds ” says Diehl With his mild Oklahoma winters Diehl’s beds usually produce vegetables from March through Thanksgiving At that point he drains the beds and disconnects the flexible pipes However he keeps the pump circulating water between the sump and fish tank He admits the process has had a definite learning curve “If you try a tomato variety and it doesn’t do well don’t give up on tomatoes ” he says “Try other varieties to find ones that fit your system ” Diehl added red wiggler worms to the grow beds “They help mineralize the fish waste ” he says “The plants get nutrients from the fish waste but they need available minerals too ” Another important step is selection of rock for the 12-in deep grow beds “I used thicker river rock at the bottom and thinner smaller particles on the upper layer to help hold the plants upright ” says Diehl Even how the rock is delivered can be important While the river rock had been washed it picked up enough lime dust to create pH problems for the fish Other lessons learned include careful selection of food-grade totes Diehl notes that the plastic can soak up whatever is stored in it and fish tend to be sensitive Diehl initially painted his tote exteriors to discourage excess algae growth on the interiors He used a flexible black plastic paint on the fish tank and less expensive primer on the grow beds It’s something he will avoid in his new larger system “The grow beds will have wood sides and be lined with heavy plastic ” he says “I’ll line the tote cage with a low cost tarp and slide the tote back in It should have the same benefit last longer and be easier to do ” Contact: FARM SHOW Followup Jason Diehl 10201 Banner Rd Lexington Okla 73051 ph 405 255-1249; www reddirtoasis com

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