If no fish are present, you can use Ag Lime for long term pH and Calcium Carbonate benefits, and use Hydrated Lime (Calcium Hydroxide) to clear the water. If you use the Hydrated Lime, wait a couple weeks for the pH to drop back below 8.5 before adding fish. You can use and grade of Alum (AlSO4 Aluminum Sulfate) at a rate of 50-75Kg per acre foot of water.
