f/2 Fertilizer (Guillard's Recipe)

This fertilizer comes from the original formulation, called "f Medium" that Guillard and Ryther introduced in their 1962 paper on the growth of phytoplankton, but reduced by half (f/2 medium).

This 500 mL concentrate is mixed such that, when 2 mL of fertilizer is added to 1 gallon of saltwater, the resulting solution will be f/2 medium.