WWW.WAS.ORG • WORLD AQUACULTURE • MARCH 2016 55 6-mm barbed male adapters into header pipes. Three holes were drilled and tapped into each header pipe. Each barbed male adapter was wrapped with teflon thread sealant to insure a watertight seal prior to threading onto the header pipe (Fig. 12). The connection from the header pipe to the individual animal holding tanks was fairly straightforward using a combination of vinyl tubing and rigid cross-linked polyethylene (PEX®). To set up tank fill lines, 6-mm vinyl tubing was attached to barbed male adapters in the header pipes (Fig. 12). An inline valve cock and additional vinyl tubing was attached which terminated at a quick connect elbow placed at the right front corner of each tank to allow diversion of water into tanks. Turn tank lids upside down and drill a hole in the right front corner. Flipping the tank lids upside down allows flexible tank fill lines to conveniently nest in the tank lid. To get water into the tank and create a sturdy connection, once the lid was drilled, add a piece of rigid PEX tubing to the bottom half of the quick connect elbow and place it through the hole in the lid (Fig. 13). As an additional precaution, drill a hole in the center of every lid to allow any water that might accumulate from leaks or condensation to drip into the animal holding tank rather than onto the floor. From the outlet of the UV sterilizer, water supply lines were extended to each header pipe. Supply lines consisted of a 1.9-cm diameter PVC pipe upright with horizontal branches running to each header pipe. Just prior to the entrance to each header pipe, a ball valve was installed to adjust flow as necessary. Supply lines empty into the header pipes at the back of the shelving unit. Extend the 1.9-cm supply line into the 5.1-cm header pipe a few inches to ensure that splashing does not occur as the header pipe is filling. An overflow return line empties into the second sump tank. The overflow return line was plumbed off the bottom of the main fill line manifold and into the second sump to avoid disturbing any solids that may have settled in the sump where the solids capture tray is located (Fig. 14). When locating the effluent manifold, measure the height of the installed bulkhead fittings on the animal holding tanks and locate the effluent manifold approximately 5.1 cm below level. Secure the effluent manifold to the U-channel with pipe clamps and nylon bolts. Set up the discharge lines for each holding tank in a given row to empty into a common effluent manifold. Each row’s effluent manifold was connected to the others on one side to return the effluent to the solids capture tray in the sump tank for primary filtration. Summary Ultimately the decision to build a rack system or purchase a commercially available unit lies with the individual. In our situation, the benefits of building a rack system with specified design parameters outweighed the cost of buying a commercial unit. Doing so allowed us to tailor the system to our space, needs and scale. This article provided some guidelines and insight into the experience of constructing an aquatic rack system. Pre-made systems are excellent products that function well. However, there are many benefits and satisfaction in taking the time to construct your own aquatic rack system. Notes Grant Blank and Dennis McIntosh*, Delaware State University, 1200 N. DuPont Hwy., Dover, DE 19901, Phone: (302) 8576456; Fax: (302) 857-6402, dmcintosh@desu.edu * Corresponding author FIGURE 13.Holding tank with upside down lid, fill line with quick connect elbow and rigid PEX fill line. FIGURE 14. Sump tank showing fill line overflow and effluent line with solids capture. Ultimately the decision to build a rack system or purchase a commercially available unit lies with the individual. In our situation, the benefits of building a rack system with specified design parameters outweighed the cost of buying a commercial unit. Doing so allowed us to tailor the system to our space, needs and scale.
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