This thought popped into my head from experience. As long as his stools arent floating I wouldnt play too much with the enzymes, but definitely look at other things. MY daughter (no CF) has HUGE stools. Its amazing that they can come out of her butt (TMI LOL). She has always been prone to constipation and one thing that triggers it is too much milk &/or not enough water. She doesnt get gass etc so its not lactose intolerance. Her stools dont float like CFers can, but definitely influenced by what she drinks. More so then what she eats. Good Luck!