I don't think the hay will hurt anything but I just don't know. I've read from Biologists who have recommended it for Algae control.

I doubt that adding of the other water will help or hurt. You will get some of everything and we all do it inadvertently from time to time. There are dangers involved but the other pond is adjacent and wading birds and other wildlife will "carry" organisms anyway.

Have the alkilinity checked. None of this stuff is much good if your alkilinity is too low. I don't know enough about your region to make any type of call on that.

It's not about the fish. It's about the pond. Take care of the pond and the fish will be fine. PB subscriber since before it was in color.

Without a sense of urgency, Nothing ever gets done.

Boy, if I say "sic em", you'd better look for something to bite. Sam Shelley Rancher and Farmer Muleshoe Texas 1892-1985 RIP Grandpa