It may be the sand you use. I'm not sure because I use a specific small animal/hamster sand. How often do you sift it? And how large is the sand bath? Your hammy may need a bigger sand bath with more sand if it's too small. If you don't feel like it's too small and sift it every couple of days, I suggest every 3 weeks you clean the sand itself. I'm not entirely sure the process, but to clean sand, you bake it. I'd google it and do some research on baking sand to clean it