The dangers of disinfection

So believes Kari Attramadal, from SINTEF Ocean, whose recent experiments have revealed that disinfection of filters can create favourable conditions for pathogens.

“Disinfection kills all bacteria, and those that grow the most rapidly are the first to recolonise the system. The most opportunistic bacteria thrive, at least in the beginning, and these opportunistic bacteria are often pathogens,” explained the researcher at this week's Tekset conference.

“Most bacteria are good or neutral,” Attramadal observed “but in farming it is generally not isolated pathogens that are harmful, but rather opportunistic microorganisms that exploit weak fish.”

She highlighted that instead of relying on disinfection, it is more important to remove organic material from biofilters using water, as a means to decrease the bacterial load in the system, without presenting an opportunity for opportunistic and harmful bacteria to exploit.

“It also helps if the water in the system has been in the system for a long time,” she pointed out, “as this favours slow growing species of bacteria.”