Hi to all and thanks for getting back to me so promptly. i will try to give you some more information on my pond etc. first, yes i have fish in the pond. a freind of mine planted 5 small mouth bass about a year ago and they appear to have spawned. i see many fingerlings approx 1-2" long. Second the system i purchased was from a nearby pond supply place. i am not sure of the brand as that was cut off the manual but i will describe it as best i can. its a pa33 aeration system consiting of a single membrane defuser. it comes in a plastic tray approx 18"X12"X4" deep on top of the tray there is a pipe about 4" up the defuser screws into the pipe. the defuser i think is about 8" in diameter. i would estimate the defuser is about 8" from the bottom. you fill the tray with rocks to weight down the system. the system also cantained 100' of weighted tubing the tubing runs about 75' from the house to the edge of the pond. the pump is a gast 1/4 hp rocking piston type pump. model 74-r. as earlier stated i placed it in about 6' of water and has been running 24/7 since july 2nd. i have not noticed any fish kills and the water does not have a rotten egg smell to it. i took some initial temp readings before i started the pump. the surface temp on july 1 was 78F. at 5' it was 67f and at 8' it was 63f. the visual clarity was approz 36". i had a ph test done and it read 8.5 i live in bellingham wa apprx 30 miles from the canadian border in western wa. my elevation is appozx 50' above sea level. the pond may have some underground springs but mainly is filled with rainwater. i plan to draw down the pond about 3' this fall and get a trac hoe in to cut down the edge and fill the sides with rock to keep the vegatation down arround the edges. i hope i have given you enough information. if not let me know. this is a wonderful sight and i am looking foreward to learning more about ponds