Give him two 1 oz. Scoops once a week.
My Arabs get one 1 oz. Scoop per week, and my TB gets two 1 oz. Scoops per week.
I use the sugar free orange flavor. The horses, especially Casper, seem to like it. Casper likes anything orange flavored.
I usually dissolve it in water and pour it over their feed, but some folks just pour it over dry.
Sand Clear and Metamucil both have psyllium, which is the ingredient used to prevent sand colic.
If you look on the premade electrolyte containers, the active ingredients are iodized sodium (salt) and bicarbonate (baking soda). Making my own is much cheaper.