Not sure if it helps but I use a couple of bags of lime in my 1/10th acre pond to sterilize it and kill any fish I was not able to get out of the pond before refilling. However that is once I've drained it down completely and have a couple hundred gallons of standing water.

That's not a lot of water at 3 feet. I would pump down as far as possible and then apply the lime. That is if you have a way to fill it again.

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.