I don't have personal experience with this, so please take it with a grain of sand...uh...salt. Ha. (My attempt at being funny.....hmmm.)
Anyway....I spoke with a breeder a while back who had a lot of problems when his axolotls bred with sand substrate in the tank. He said that a good deal of sand stuck to the eggs, and it was impossible for him to get it off the eggs. He said that a large number of his tiny larvae died from impaction because they apparently ingested tiny grains of sand.
It seems like others have not had this issue, but I thought I'd just mention that it is a possibility.
Sharon