I have a 5000 gal lined pond, about 12 years old, with goldfish. I have had green water before, but always cycled itself out. This year, I believe that someone sprayed fertilizer around my pond. Got green, did a 500 gal water change, and it kept getting worse and worse. We are on a well, and this summer, am in a severe drought area, so water changes had to stop. I tried shop vacing the bottom - was ALOT of sludge on the bottom, that is now floating to the top. I have not lost any fish, and am only feeding every 3 days. I want to drain the pond, put the fish in a plastic swim pool, and clean the pond completely, and lightly spray wash it down. Only problem, I need to wait till mid September to make sure my well can handle cleaning out the pond. I plan on having water delivered - and will slowly add the water to the swim pool to adjust the fish to the new water. My problem is, living in Central NY, cold weather starts to come around Mid Oct. Is there any thing I can add to the new pond water, to get the bacteria going before winter freeze. It has to be cleaned before winter - I know the fish would not survive the ice buildup on the pond. Any help, any ideas would be greatly appreciated.