Modified planktonkreisel tank design. (A) Showing the half-circle culture chamber, the airlift loop, that draws water from compartment ‘A’ to compartment ‘B’, and the baffle that directs the water downwards into the culture chamber. (B) Showing the interchangeable mesh inserts, the standpipe and airlift loop inlet in compartment ‘A’ and the airlift loop outlet in compartment ‘B’.