COMPARISON OF NFT AND RAFT TECHNIQUE USING L.E.D. LIGHTING AND BASIL IN AN AQUAPONICS SYSTEM

John Derksen*, Montserrat Villanueva-vorvolla Aquaculture Centre of Excellence Lethbridge College 3000 College Drive South Lethbridge, Alberta, Canada T1K 1L6 j.derksen@lethbridgecollege.ca
To compare growth potential between two common methods of aquaponics production, Nutrient Film Technique (NFT) and Raft, an experimental setup using 4 identical 5' x 5' x 8" grow trays, connected to a common fish tank was constructed. Two of the growth trays, representing the NFT, were equipped with 10 parallel sections of evestrough connected to a perpendicular trough section, which sat in the grow bed area. Water was received in the perpendicular trough section, which distributed the water evenly to the parallel troughs. Styrofoam plant rafts (Beaver Plastics) were placed over the troughs with the roots of seedings hanging below in the trough water. The two other grow beds, representing the Raft systems, were simply filled with water over which a styrofoam plant raft (61 plants, 8 inch centres) was floated. Water level was controlled with standpipes and the sole lighting was provided by 4 L.E.D. lights (GrowPro 600 Watt). Six grass carp (Ctenopharyngodon idella) approx. 500 g/fish were fed 100 g commercial diet/day and provided the only nutrients. 61 seedlings of Genovese Basil (13 days) were introduced into each grow tray and plant height monitored over the course of 33 days, at which time all plants were weighed and leaf weight samples taken.
 
Plant height (growth rate) of basil in Raft systems was consistently greater over the course of plant development and approx. 15% > by day 33 (Fig. 1). At the conclusion of the study (day 33) the weight of all plants were measured and recorded and it was found that the production of basil in NFT and Raft systems was identical (Fig. 2). The results indicate no preference for either NFT or Raft aquaponics systems in growing basil using l.e.d. lighting from a plant growth perspective, however overall maintenance and system efficiencies should also be considered when selecting an appropriate method for aquaponics production.