|WILLS, PAUL - Harbor Branch Oceanographic Institute
Submitted to: Global Aquaculture Advocate
Publication Type: Trade Journal
Publication Acceptance Date: 2/11/2009
Publication Date: 3/15/2009
Citation: Pfeiffer, T.J., Wills, P. 2009. Researchers evaluate low-energy recirculating system for inland production of marine finfish juveniles. Global Aquaculture Advocate. March/April 2009. p.44-46.
Technical Abstract: The low-energy recirculating aquaculture system consists of nine separate modules which utilize the double drain fish culture tank paired to a moving bed biofilter. The nine fiberglass tanks are five feet in diameter and normal water depth is about three feet for a total tank volume of approximately 440 gallons. The double drain of each tank has a central sump 10 inches in diameter and four inches in depth. A 1-1/2 inch diamter drain line from the center sump is used to purge the accumulated solids from the sump. A slotted 2-inch diameter center standpipe is used in the transport of mid-column water from the tank to the moving bed filter. The center standpipe fits into a bulkhead fitting at the bottom of the sump which is then plumbed to the biofilter via an approach pipe that is 2-in diameter. Shallow fins on opposing sides of the center standpipe act as a vortex breaker for water around the standpipe and aid the in-tank solids transport to the center drain sump. All piping and fittings are schedule 40 PVC. Water is air-lifted into the biofilter and the air for the moving bed filter systems is supplied by a 3.5 hp, 3-phase regenerative blower. The filters are filled with approximately 4 ft3 of floating plastic media. Media movement is obtained by placing a 5-in diameter snap-cap, flexible diaphragm, coarse bubble diffuser below the media and aerating the media to create a torroidal movement pattern of the media within the filter. The air lifted water flow through the filters gravity flows back into the tanks and can range from 5 to 20 Gpm depending on the amount of air supplied into the riser pipe. For the most part, flow through the filter is approximately 16 gpm which provides the tank with two turnovers per hour through the biofilter. This recirculating aquaculture system has been utilized in the Phase I (1 to 2 inch standard length juveniles) through Phase II (2.3 to 4 inch standard length juveniles) production of red drum. Future objectives are to evaluate the system for the year round juvenile production of Florida pompano (Trachinotus carolinus), cobia (Rachycentron canadum), and other potential high value marine finfish species.