Dark Waters
This spring the water in the pond was so dark we had trouble seeing the Goldfish. The last time this happened, it was an abundance of green algae. I solved the problem with a UV filter. It worked well for a number of years until now. I suspected the UV bulb was dead but first I checked the filter and it was clogged with slime. I cleaned it and a couple of days later the pond water was getting cleaner. The process takes a couple of weeks so we know soon if the problem is solved but at least I have a better view of the fish.