The raft system uses filtration components that allow higher stocking densities of fish and, therefore, a higher production of plaints.
One of the unique advantages of the raft system is that high volumes of water in the system acts as a buffer for the fish. In a typical recirculating aquaculture system (RAS), fish are stocked at a higher density.
This high stocking rate makes managing the water quality and health of the fish very important. In raft aquaponics, all of the water is recirculating all of the time. Monitoring and managing water quality is a must.
In the past this was concerted the dirty part of the job. Now with improved filtering and use of materialization process this can be done more efficient and without a lot of manual work as in the past. Since the largest surface area (the raft tanks) is covered by the rafts, evaporation is minimal.
Every day you replace the water that has been used in transpiration by the plants, a small amount used in cleaning the filter tanks and what is lost to evaporation.