I have a 2,000 gallon, two 1,500 gallon and a1,000 gallon pond. I also have two small ponds just outside the house I forgot about.
I tried different filtration systems and none seemed to work. I seem to have some green water no matter what. But I did try something new that really seems to help. At the last fishing trip I netted up a bunch of river shad. They are filter feeders and the green water seems to be clearing up. The ones that survived the trip went into the ponds and the ones that didn't went into my pigs.
I move the water around during the hot months but right now I have no filters running at all. It (to me) is a waste of money.
I do have one pond in a shady spot with a lot of plants in it that stays clear until I pump it into the other ponds and put green water in. I guess that is my filter.
Shade would probably help but that's another iron in the fire. I keep pretty busy and it is hard to keep up.
Thanks for the info! On my smaller ponds (130 gal above ground), DH finally made a bio filter with gravel and plants. It always stayed crystal clear, but the pumps were killing my electric bill. I think we'll go back to a plant bog type bio-filter. Seems to be working for you as well.