it may sound like a broken record, but time controlled bottom diffused aeration has kept my FA negligible while the water still maintains planktonic algae.
i aerate from 11 pm to 8 am nightly for a pond that is now about 2/3 acre due to drought. i have two sets of diffusers, one in a channel up in the shallow end, and one in the deep end. the aeration has also kept what i think is coontail from taking over, and has kept the pondweed confined to a rim around the edges of pond.
