An integral part of shellfish aquaculture is the nursery phase. It follows the hatchery phase where the shellfish are spawned, swim in a larval tank for a couple weeks, then metamorphose from free swimming larvae and “set”, in the case of oysters on some substrate, and for clams onto the bottom of the larval tank. The next step is usually a downweller where phytoplankton-rich water runs into the top of a silo that sits in a tank of sea water. This technique keeps the newly set and extremely light post-set from flowing up and out of the silo. When they grow a bit larger, the tiny seed can go into an upweller silo. The water will enter from the bottom of the silo and flow out through a fitting in the side of the silo. Seed will stay in the upweller until they are either moved into a growout phase, or put into a raceway for further growth before field planting (Figure 1).