Formulated diet may experience rapid leakage of nutrients when immersed in water (Baskerville-Bridges and Kling, 2000;Kvale et al., 2006) and the accumulation of particles may result in increased nitrogen concentrations in the system. Particles can alsoreduce the effect of disinfection by providing shelter for bacteria and viruses (Hess-Erga et al., 2008; Hess-Erga, 2010).