52 MARCH 2016 • WORLD AQUACULTURE • WWW.WAS.ORG are numerous options, each with its own merits. Glass aquaria are readily available and fairly inexpensive, but drilling holes in glass is difficult. With acrylic aquaria, drilling holes is easy but aquaria are quite costly. We used polycarbonate food storage containers as animal holding tanks. They are inexpensive, readily available in appropriate sizes, and easy to drill holes through. Before making any purchases, make any necessary revisions to the sketch based on the dimensions of selected components and/ or availability of specific parts. Sourcing can seem like a daunting task. To help spark creativity in sourcing parts for a rack system, an example of a supply list is provided in Table 2. In creating a shopping list, include product descriptions, store names, and item numbers for future reference. Supplies can be obtained from local stores, specialty supply catalogues and the internet. Using local sources and the internet can result in cost savings on many components. Starting Construction Shelf System Assembly. Gather the necessary tools (Table 3), including a tape measure, reciprocating saw (Sawzall®), ½” electric drill, drill bits, and hole saws. Begin by assembling the shelf units. Assembly should be relatively straightforward because most commercial shelving units are provided with directions. Preparation of Animal Holding Tanks. For the animal holding tanks, we used 24, 18-L Cambro Camwear® food storage containers. Before use, several modifications to tanks were required. To facilitate observation of animals in the rack system, water was designed to flow from the back of each tank. Determine the maximum water level in each tank and mark the location. Cut a hole through the back of each tank with a hole-saw blade of the appropriate diameter and install a 1.3-cm bulkhead fitting. When drilling through polycarbonate tanks, put a solid support beneath the tank where the hole is drilled because cracking or breakage can occur. Once bulkhead fittings are installed in each tank, add a short length of 1.3-cm PVC pipe (Fig. 3). In addition, drill a 1.0-cm diameter hole into the front right corner of each tank as a water inlet. After drilling inlet and outlet holes in each tank, water supply and effluent return lines can be installed. Sump Tanks. Sump tanks are placed below the two racks and joined in the middle (Fig. 2). Sumps serve as a water collection point for the rack system and the location of immersion heaters, pumps, solids capture, biofiltration media, and aeration. For sump tanks, we used four 75.7-L (40.6 cm × 45.7 cm × 40.6 cm) polyethylene tanks. To set up sump tanks for use in the system, several holes were cut with a hole-saw of the appropriate size, a jigsaw, or other tool. We used a Dremel Trio™ with a hole-cutting attachment. Lay out the location of all necessary holes (Fig. 4) of each sump tank. This includes one large top hole for access and two additional round holes for bulkhead fittings in each of the four tanks. Two tanks had one hole for a 1.9-cm diameter bulkhead fitting and one hole for a 7.6-cm diameter bulkhead fitting; the other two tanks had one hole for a 7.6-cm diameter bulkhead fitting and one hole for a 10.2-cm diameter bulkhead fitting. Although individual hole locations are not critical, ensure that adjacent holes are properly aligned to allow leak-free connections among the four 75.7-L tanks. Drill holes from largest to smallest to aid in tank alignment. We wanted the flexibility to run the rack system as two separate banks of 12 tanks or a single bank with 24 tanks (Table 1). This was accomplished by joining the sumps in each bank with a 10.2-cm diameter bulkhead fittings and PVC pipe to allow water mixing between the two units (Fig. 5). It is possible to separate the FIGURE 4. Polyethylene tanks are used for sumps, once holes were cut in the top to allow for internal access. FIGURE 5. Sump tanks connected together. Note the cutout and bulkhead locations with additional bulkhead gasket between the two tanks to ensure a good seal. FIGURE 6. Heater mounted to sump tank. Inset: PVC spacer used to hold heater away from sump sidewall.
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