Mike, one more thing--it's worth thinking about whether the lack of clarity is suspended clay vs. organic matter, live, decaying, or otherwise. We have a 3/4 acre clay pond, filled entirely by runoff. The clarity for the first couple of years was essentially nil, and with guidance from Cecil Baird on the Farm Ponds board I was able to use jars of water to determine that I had ionically suspended clay in the water. I applied alum (aluminum sulfate) and the clarity has since been far better. It's an easy test to run, but it sounds like you need to focus on oxygen issues first. Good luck!
