Embodiments of an implantable electrolytic pump include a first expandable diaphragm and a second flexible diaphragm, and first and second chambers each for containing a fluid, wherein the first expandable diaphragm separates the first and second chambers and provides a fluid barrier therebetween, and the second chamber is formed between the first expandable diaphragm and the second flexible diaphragms. The pump may further include electrolysis electrodes within the first chamber for causing generation of a gas therein and to thereby expand the expandable diaphragm so that fluid is forced from the second chamber into a cannula.