As a part of CEEF, a hydro-sphere experiment system has been installed in the air-tight hydro-sphere chamber built in fiscal 1997.Environmental factors in the chamber such as air composition, temperature and humidity could be fully controlled from 360 to 2000ppmCO2, from 20 to 30°C and 70%RH respectively using air composite adjusting system and air-conditioner.In this chamber having 640m3, three aquariums having 20m3 volume each have been installed. One of those aquarium will be used for the sea water buffer, the other two will be used for breeding living organisms such as small animals and macro-algae.A water reclamation system also has been installed in addition to those aquariums, and sea water is to be circulated at the rate of 20m3/3days between those aquariums and this reclamation system in order to realize the simulated sea water eco-system.The water reclamation system is composed of a membrane filter and bio-filter.Solid waste, difficult to be decomposed, is extracted, and the residual organic material is decomposed, nitrified and denitrified in the bio-filter.Solid waste coming from the membrane and bio-filters is to be burned using the incinerator installed in the outside of the chamber after dehydration, and residual ash is dissolved using the water coming from the sea water buffer and returned into aquariums. A part of the solid waste also can be returned directly into aquariums after vapor sterilization.The water temperature in the two aquariums for living organisms is to be controlled between 10-20 degrees Celsius using the water temperature controllers, and the tidal level can be simulated by changing water level in each aquarium using pumping systems.Outside the chamber, a Phytoplankton Culturing Subsystem will be installed. Phytoplankton culture can be conducted for providing the feed of living organisms in the aquariums using air and sea water in the inside of chamber.In addition to this hydro-sphere experiment system a high pressure tank system (up to 7MPa.) has been installed in the outside of the chamber for studying to mechanisms of alkaline pumping and bio pumping about the CO2 exchange between atmosphere and hydrosphere.