Theo,
I went swimming in last weekend. My wife thought I was nuts. She said "It's all GREEN in there!"
I stuck a bottled water in the pond and held it up to her and she couldn't believe it looked like Aquafina
I have about 30-36" of visibility now, where it was zero in November. Some of the spots are 30 feet deep in the pond.
A lot more fun at feeding time, too!
chuck