I have 2 RES, 1 about 7.5 inches and 1 about 6 inches. Up until recently, I had them in a 50 gallon tank because I couldn't find anything bigger that was affordable for me. I recently acquired a 200 gallon tank and I just set it up today. I filled the bottom with normal fish gravel, as when they were hatchlings they had that in their tank (though they haven't had any gravel for the past 2 years). I then noticed them trying to eat some. My smaller RES would chew on it and spit it back out, but my bigger one, which has always been a bit of a glutton, just swallowed them. I had to leave the house due to an emergency and couldn't remove the gravel right away. I removed it when I got home, but they were still with the gravel for about 8 hours. I saw the bigger one swallow about 3-4 small ones.
I've heard that they can pass it on, but that it can sometimes cause problems. They still seem fine and very active right now, but the problem is that I'm going away to another city for the next 3 days and can't watch over them to make sure they're passing the gravel. I can't even ask my dad, who lives with me, because he's the kind of person who barely remembers to feed my turtles, let alone watch over them. What should I do?