Optimum control of a closed ecological system (CES) is not possible without adequate CES description and appropriate evaluation of factors, which act upon the system and introduce additional errors and uncertainties into the forecast of the CES state. The statement about key significance of stationary state consideration for further CES development is supported. In this article some of the disturbing stationary state factors and the contribution of them to CES state formation are considered. An approach to outlining the optimum set of chemical elements--the balance of which has to be calculated--is presented. An example of the minimum description of CES stationary state is considered.