I lost my first gecko to sand impaction. I would send you some poop too but that was almost 10 years ago and i discarded it. LOL I currently use a soft,fine woven cloth material for my gecko enclosures. Their nails don't get stuck,its soft,it looks like sand,and it can't cause impaction.
(I haven't lost a gecko since I stopped using the sand. By the way, impaction can take days to years before it is a problem.)