Was thumbing through some of the articles on here and online after recently finding both my Nerite snail shells with cracks. They're not very deep everyone seems to be acting normal. But i've noticed some others on here had their shells crack not too long after getting them or just in general. I've had mine about 3 months. My pH is 7.4 . I'm assuming it has something to do with my hardness. I also don't add calcium, and I do not believe they are deprived of food. Should I be watching for them becoming less active and eventually die from these cracks?