So I have big fly problems in the summer, especially when it is wet. I have been using hay, but now have learned that hay isn't actually the best to use and can actually attract flies. So, I am wanting to switch to sand. I know that sand can't be too fine and dusty or else that will cause respiratory problems. I've read that washed sand is good because there is less dust, but the washed sand I've looked at still have warnings that talk about respiratory problems. Any suggestions on what sand I should use that would be safe?