If you build the brush pile too big the crappie will be scattered. You ll find that the crappie will be at different depths on different days. This way you can fish a brush pile at a depth of 20 feet, one at 14 feet and one at 6 to 8 feet. Whatever depth you catch the first Crappie, then simply fish the brush pile at that depth. You will find if you catch fish on this side of the lake at 6 feet, then you will catch fish on the other side of the lake at 6 feet.
Fish know more about high and low pressure than any weatherman on television.
I believe that the pressure is the major factor that determines the depth of the fish. Anytime you find your brush piles full of crappie, you can bet that there is a large-mouth bass near this area. You can expect to lose a couple of jigs every now and then. Bury your brush piles deep enough that they are not readily visible. Locate the brush with your depth finder and place a bouy-marker right on top of the brush pile.