As a winter project I am modifying my sluice. I have a grizzly/classifier mounted above. What I want to do is put a damper where the material dumps in from above to create a fluid bed so the larger gold can settle in the mat and also to smooth the flow as it begins it's decent. My question is what type of material to use. How flexible does it need to be, and much can I dam the water back. I was thinking of squeegee rubber as it is fairly flexible but was wondering if anyone has a better idea based on their own experience.