Thanks for the advise. Think I start changing some water in the next few days. My aerator keeps my water from freezing so there is some movement in the water. I like the idea of the salt and will also add as well. As for the devil, I made my pond 3-4 feet, no shelves. I have a good deal of fishing line just in case he or she attemts to fish from the sides. This one is a male. He is very large! He has yet to land in the water from what I can see.He actually will fly from the perogla to my pool cover then walk under the perogola. In the past the pond was shallow and he would wade right in. He normally only comes after the bait fish disappear from the bay (around late september) and we wouldn't see him until next year. I assume its because of the mild winter. He sits on the perogola while I'm not home for hours staring at the pond. When frightened he retreats to my neighbors rooftop. The aerator is so strong I wonder if he can even see the fish. They are huddled in the deepest part of the pond hidden under a large flap of liner.