Mechanical problems are also common in hatcheries and ongrowing systems, derived, in the first place, from bad design or bad management (i.e. resulting from unexpected conditions). This pattern is created because consultants and suppliers specify that the cheapest equipments are used to meet the demands of the producers for low capital investments. The solutions given for this problems are quick repairs and in last resort replacements. Indeed, this extra capital expenditure due to rapid repairs and replacement were the reason that leaded to some farms to close the business operation. Typically, the most replaced devices, due to a RAS failure,
are disinfection devices (i.e. ozone and UV), pumps and biofilters (e.g. 50% of the times when a biofilter or a pump has been replaced, it was for a RAS deficiency, 75% for O3 and 66% for UV devices). Moreover the connecting pipework and drainage pipes had also been reported as being problematic, undersized and not effectively designed (e.g. slope), respectively. Issues included here directly affect the oxygen amount in the tanks. Another effect is that lower water velocities cause the settlement of solids and/or growth of weed, i.e. compromising the water quality. As an outcome, eleven out of seventeen companies were rebuilt or redesigned completely,
following their initial installation; 50% of them due to deficiencies in RAS, whilst the other 50% mainly to extend the production capacity.