The dynamics of seston and dissolved elements in a meromictic lake with high concentrations of manganese and iron in the monimolimnion were studied through an annual cycle. This publication presents results for assimilation, sedimentation and recovery of nutrients (C, N, P, and Si) in the trophogenic zone. Phosphorus deficiency kept the productivity of the diatom dominated phytoplankton at an oligotrophic level. High concentrations of iron in influent streams and redistribution followed by precipitation of iron during periods of partial turnover removed phosphorus from the water. High concentrations of manganese and sulfate did not have the anticipated fertilizing effect, and recovery of nutrients from the depth of the lake was negligible. Mass balance calculations indicate that liberation of phosphorus from the sediments in the trophogenic zone was most important for the maintenance of primary production. 75 % of carbon, 80 % of nitrogen and 25 % of phosphorus assimilated by the phytoplankton was mineralized in the trophogenic zone. Silica was effectively regenerated from the littoral zone during the decline of diatom blooms. Nitrogen and silica retention was 45% of the external load compared to 66% for phosphorus.