JANDY RESIDENTIAL DEV DIATOMACEOUS EARTH (D.E.) FILTERDiatomaceous earth is a natural, eco friendly water polisher. Made of tiny fossil exoskeletons, diatomaceous earth is a safe and natural water polisher. The DEV filter traps debris as small as 5 microns, returning highly filtered water to your pool. DEV filters have a curved grid design that creates balanced water flow throughout the filter tank, and are constructed with a heavy duty, durable composite body made of corrosion and UV resistant