Water filtration in aquaculture and RAS
Reliable water treatment is fundamental to any intensive aquaculture operation. Fish, crayfish and shrimp production continuously introduces suspended solids, feed residues and metabolic waste into the water. In recirculating aquaculture systems (RAS), these contaminants remain within the process loop unless they are efficiently removed or biologically converted. A well-designed filtration system therefore has to manage both solid waste and dissolved compounds while maintaining stable water flow throughout the facility.
CrawTec designs and manufactures water filtration equipment for aquaculture facilities and RAS installations. Our range includes drum filters, combined filters, biological filters and complete filtration systems. Equipment can be integrated into an existing facility or configured as part of a new water treatment system according to flow rate, production load and the requirements of the cultured species.
Mechanical and biological filtration
Effective solids removal is the first step in reducing the waste load within a recirculating system. Drum filters continuously separate suspended solids from the main water flow and automatically discharge the collected waste during the cleaning cycle. Removing solids at an early stage helps prevent organic matter from accumulating within pipework and biological treatment units.
Biological filtration performs a different function. Biofilters provide the environment and surface area required for microorganisms involved in the conversion of dissolved nitrogen compounds. Mechanical and biological filtration should therefore be considered complementary processes rather than alternative technologies. Their correct integration is one of the key factors in maintaining stable water quality in intensive aquaculture.
Filtration systems engineered for the application
There is no single filtration configuration suitable for every aquaculture facility. System design depends on water flow, stocking density, feeding rate, species, production technology and the required water quality. An installation may use separate drum and biological filters, a combined filtration unit, or a complete multi-stage system incorporating several treatment processes. UV equipment and other water treatment components can also be integrated where required.
CrawTec manufactures its filtration equipment in-house and can adapt system configuration to the technical requirements of each project. Rather than selecting equipment solely by nominal flow capacity, we consider how the individual treatment stages operate together within the complete water circuit. This approach makes it possible to build a balanced filtration system for anything from a compact RAS installation to a larger commercial aquaculture facility.
Drum filtration in operation
Drum filters are widely used as the mechanical filtration stage in modern RAS and aquaculture facilities. They continuously remove suspended solids from the circulating water before these contaminants reach downstream treatment equipment. The video below shows a CrawTec drum filter operating under real working conditions.
Bakki Shower biological filtration
A Bakki Shower is an open biological filtration system in which water passes through exposed filter media with intensive air contact. The highly oxygenated environment supports biological activity on the media while also providing additional aeration as the water moves through the filter stages.
Bakki Shower filters are particularly popular in koi systems, but the same principle can be incorporated into other biological treatment configurations. When installed downstream of a drum filter, the mechanical stage removes suspended solids first, allowing the shower filter to focus primarily on biological treatment.