I no longer use any type of shavings, but back when I did I would put a fine pine on the bottom to help absorb the urine and then bed with a larger pine/cedar mixture for the top. I would use more cedar in the summer when the flys were worse it seem to cut down on them. I noticed that my horses in a cedar/pine mix had far less fly's in their stalls verses the horse in the same barn bedded on just pine. Although I now absolutely love not messing with shavings at all. Sand is the way to go for me.