Pond Boss Forums INTRO Questions & Observations follow up on fish kill

I posted about a fish kill in the help area, here is a follow up and a few questions. One acre lake in SW Ohio, aerated since May, no feeding, average depth 8-9 ft,stocked 200 3-5" bass, 400 bgill, 200 hybrid bgill in spring 2000. Bass now about 11 to 13", bgills 5 to 6", hybrids 6 to 8". Lost about 100 bigger bgills/hybrids, and about 5 bass to low DO( that I could see floating), following a large bloom caused by runoff from a crop field close to pond. Seemed to follow 3 to 4 cloudy days, and seemed to only happen once( all fish at same stage of decomp). Fished early one morning this week and caught about 12 avg size bass (12") and few big bgills.
What should I do to stop/reduce chances of this happening in the future? Would a fountain run for the really hot months help? Any other ideas, this is my dream and while I shouldn't have placed it near a field, it's too late now. I have about a 50 ft grassy area between the field and pond. I also plan to log my catches and see if I lost more fish that I don't know about, my wife and I have fished this summer, so I have a rough idea of how the fishing should be.
Thanks for any ideas and great forum!!

I don't know the answer to how to prevent this if there will be more heavy fertilizing going on in your drain field. But I did want to say that you do not get a fountain. A fountain aerates the top layer of water, which does not need aeration. You need a bottom air diffuser. It adds air to the bottom layers of water, which need more air, allowing beneficial bacterial to thrive on the bottom, eating sediment which fills your pond. It also stirs the water, keeping it from stratifying.

How does the runoff water from the field flow into your pond, through a ditch? creek? across the surface? Depending on how it gets there you may be able to trench around the pond to divert some of the field runoff. Or is this your main source of water for the pond?

Just to verify, the fish kill happened approx. 4 cloudy days after the runoff and subsequent bloom? Was the pond green or brown when it happened? Much additional vegetation in the pond?

Nick, I already have a bottom diffuser, I was wondering if a fountain would help as an addition during the hot months.
Pottsy, It is surface runoff, goes through about a 50 ft border of grass and bushes. Pond was green when I saw the dead fish with a thin film of algae on top. The pond is not over crowded with plants, but did have a bloom. Went up last week, and pond looked great, except for shallow end which had a thin film of algae on top.

Thanks for the ideas, I appreciate all the help.

wE HAD THIS PROBLEM LAST YEAR jUST MADE ME SICK...wE LOST AT LEAST 1,000 FISH. LARGE 18 + BASS,CATS.BLUEGIOLLS iT WAS AWFUL. i REMEMBER SEEING LIKE A BIG RED CLOUD IN THE MIDDLE OF THE POND BEFORE THE KILL. WE WERE IN A TERRIBLE DROUGHT AT THE TIME.i DO TKNOW THEY SAY NOT TO START UP AN AREATOR OUT OF THE BLUE.cAN CAUSE hAVOC.