Besides the air injection technique, we have Dimpled the surface of the beads, to add more surface and non- abrasion area for the bacteria.
This allows for undisturbed colonies of bacteria during backwash, thus creating a bead filter not prone to stumbling after a rigorous backwashing. The size of the bead was slightly downsized, for added surface area, as well.
If your pond's surface is frozen over, Do Not break the ice, doing so could harm your fish. Instead, use warm water to melt a hole in the ice or use a pond Deicers to keep a hole open.
