We are thinking of making a mechanical Marimo(the marimo is a japanese algae that rises and sinks in the lake to get light ), that would rise and sink into the water as the user pedals on a bicycle in order to generate the air pressure necessary that the Marimo would rise. So far we think we need some sort of an air pump, a way to seal a ( 20m?) hose to it which is connected to a 100 l plastic barrel, the pump would be activated by pedaling a bicycle and thus creating air pressure, when the pedalling stops or the marimo would have reached the surface, the pressure would be released through either a valve or the pump so that the installation might sink again. The barrel which does the lifting would be inside of a spherical shape made out of plastic (maybe we could get some suggestions for better materials ) and covered with something which would resemble grass.
Just some inspiration maybe :
http://www.youtube.com/watch?v=wMEMb4qTvBk – it should work sort of like this I think, but in reverse, with a pivoting arm attached to each of the pedals and when pedaling pushing a piston back ..and pumping air
Ioan, Fabrizio & Maša