I saw a recent message on green water. I have a 1200 gallon koi pond,
and this year the water has been really dark green. I can hardly see
the fish. Will this cause the fish to develop ulcers or sickness? I
changed the filter and replaced about 2/3 of the water, but it is still
very dark. If the pond needs shade, is the answer just plants or
maybe an awning??? Thanks for any help. Dan