MrSandman,
I've recently taken a job to where I deal with ponds and pond issues. Part of my learning has been to read through this forum and see what is being discussed. This topic made me want to actually log in and not just be a reader. The company I work for has a Learning Center on their website. I was thinking this my be of help to you now, or maybe in the future. It has taught me quite a bit as I continue to learn about all this pond stuff.

http://www.naturalenviro.com/learning-center.php

I hope this helps. Not trying to sell anything, just provide information.