Use it sparringly!!!!
I thought the stuff was a God send, and it is, but I would only give it once in 24 hours and only if the foal has watery liquid stools (otherwise use pepto).
It can QUICKLY turn things completely around and your foal can go the opposite direction. It is easier to correct loose stools than an impaction in a foal.
I haven't used the powder, but in the paste, it was only 2-2.5cc for a mini foal that was needed.