Ok, so at this point my pond is usually coated by 4 to 6 inches of ice and my water is clear. (Looking through the heated hole) I am in the PA area. Nothing of harm will live in water that cold. However this year I winterized it as I always do but now the water is a deep green like it would be in the spring. (The filters and waterfalls are shut down.)The temp in my area has been from 20 to 60 and back down. The nitrogen and nitrate levels are up. Should I do a water change? Will this disrupt the fish�s normal dormant state? Will this increase the chance of the fish�s immune system being comprised as there are no good bacteria in the pond? Should I add sea salt? Oh where is the cold winter! (Never thought I would say that.)