I use DE regularly to dust their bedding area and the floor of their house. I start with a 25 lb. bag and then dump the rest in their "run" for them to take their baths in. It's not food grade DE. I get it from a pool supply house, as it is used as a filter medium. I'm not sure what the difference is, but I have not seen any ill effects (been doing this for years). Is this effective? Is there any chance I could be hurting my girls?