Try Daphnia. They feed heavily on phytoplankton. I could ship you a culture. They multiply like crazy. A thousand will quickly become 10000 in a large tub of green water, and clarify it within days. If you were to start a culture, you should grow them in a tub until you have enough to stock in the pond. I keep them in tubs, and seed them in my pond on a daily basis. They make an excellent feed source for smaller fishes. PM me if you want to know more.
