So I have decided to put a few dust bath bins inside my coop, mostly for bad weather days my flock is cooped up inside. I have found 2 of these things- that were laying around that I would like to use rather that buy or build something. However I was wondering- it is only about 3 1/2 inches deep. Will that be deep enough? I understand they might kick some of the sand/dirt out of it, but with that depth, will they be able to bathe well enough? (I have noticed outside in their favorite spots they have dug out holes that are like 8-10 inches deep) or will they just end up kicking all the bathing material out onto the coop floor? Also- I have 2 chinchillas and have some dust (made from pumice) I bought for them but didnt like it (too gritty, didnt clean them well) Is it ok to mix in with the chickens dust bath? it would only be a small percentage of the whole mixture. Thanks!!