![]() ![]() Upweller tanks can be constructed from fiberglass, plywood, barrels or moulded plastic and are designed to hold single or multiple screens depending on the water flow that can be delivered to this type of system. The example (Figure 3) is 2.7 m long x 1.25 m wide x 0.5 m deep, with a central trough or channel 12 cm wide. Plastic mesh secured with a cable tie or similar is placed over the outlet as a back-up screen to prevent spat being accidentally flushed from the screen. A small (1.5 cm) hole in the wall of the screen, opposite the outlet, is used to hold a rod or peg that braces the screen (Figure 2). This sleeve serves to bayonet mount the screen to the inner wall of the tank connecting it to the sump. An outlet (sleeve) is glued or welded through the upper wall of the screen. Fine mesh is glued to the base of the cylinder and then secured with an additional ring of plastic that is heat–shrunk around the rim of the screen. The example (Figure 2), is the most common in NSW and is made from sheet plastic that is welded in to a 45 cm diameter cylinder. Upweller screens can be made from plastic, wood or fibreglass. There are variations on this design including floating upweller systems or FLUPSYS. The example pictured (Figure 3), is a twin tank system with a central overflow sump. ![]() Seawater is pumped into each tank, which then “wells up” through the screen before passing to waste through a screened outlet into the sump. The name upweller is derived from a system in which spat are held on a screen in a tank or trough. Upweller nurseries of the type illustrated in Figures 2 & 3, are one way that these spat are on-grown to a size at which they are suitable for estuarine growout techniques. ![]()
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