I have two 4 inch axolotls in a tank and i recently added sand because the bottom looked too boring and for the first couple of days it seemed fine. When i would put food in i would noticed they would get sand in there mouth when they leaped at the food and they would spit out the sand and the food. Now a couple of days have gone by and most of the time they refuse to eat? and when they do eat they spit it right back out? what's going on? I bought that childrens play sand from home depot that everyone on here was saying was safe and would pass thru the axolotls system if indeed they did swollow sand.