Sump design

I have a 10 gallon sump design for my 29 gallon display tank. the water comes in and flows under a baffle then over a baffle into a deep sand bed and water flows all the way through the deep sand bed and comes out at the bottom where water will flow up and over a baffle into another deep sand bed and does the same thing as the first but ends into a return area. It sounds a little confusing because i cant find a good picture. Thanks!