Sodium Benonite, in the powder form also works well. It sticks to the suspended particals and falls to the ponds bottom. This is also used to help stop leaks in a clay lined pond.The benonite fines its way into the cracks and helps seal it to stop the leakage. Many contractors mix benonite into the clay soil before they compact it. When the water hits it...it expands greatly to help seal those clay built ponds when filling.
Rowly
