I have now changed to sand and its alot easier to care for, and no need to worry about them eating it.
Dont take the sand from the beach did you know it illegal? and more than anything its covered in so much c**p its unbelievable.
I got my sand from a pet shop it was called aquarium sand. I have also been told that 0.5mm silca sand is good, and know of someone that used play sand for their tank but of course well soaked and wash about 1000 times!!.
I have had pebbles in my tank but i found that my axos didnt like climbing over them and were unable to sit in a nice spot.
Mine now make little dips in the sand were they like to lay all day untill i get hom from work.