We do not recommend sprinkling it in the pool since it can take a long time to dissolve and it is acidic so it can discolor and damage the liner. If you have a vacuum, vacuum it into the filter, then do not backwash/clean the filter for a few days so it has time to dissolve. If you do not have a vacuum, then brush,brush,brush fairly often to keep it off of any one spot too long.
My preferred way of using cya is in an old sock hung in front of the pool return.