With anything that you apply to the dry ground, you have to incorporate it into the ground then when the pond fills you have to make dang sure the inflowing water doesn't scour that away. i.e. if you use a hose to fill the pond or a pipe, have the water splash out onto a big tarp so it doesn't erode the ground as it flows into the pond. If it does, more than likely you can have a leak in that spot.
With SoilFloc, if that does happen, all you have to do is apply some over that area once the pond is full.
