Did you mix the hydrated lime in water and then spray the pond? I'm guessing the Hydrated lime was just spread out. Hydrated lime when mixed, dissolved and sprayed will kill all things in minutes. The water will also turn gin clear from the milky white in about 45 minutes when the concentration is high enough
I mixed what I estimate was a few pounds with water in a 5 gallon bucket and then tried to distribute it over the surface as best I could. I then agitated the water a bit by throwing more buckets of water to encourage distribution. I had a tough time estimating how much lime was enough. I did see the water turn milky but had to leave before I could see longer term effects. It rained a small amount overnight which caused more muddy run off, so I'm not sure if the water reached gin clear status. Given that tadpoles and fish survived a 24 hour period, I'll take that as a sign to make a second application before the next rain.
I just realized I didn't clarify the area being treated. I didn't attempt to calculate water volume but I will. It was a surface area of about 2000 sqft with an average depth of maybe 6 inches. So maybe 8000 gallons?