Well I'm just experimenting but my riffles are made from half inch L channel, and I space them 5 inches apart. Don't know if it's right or not, but I'm guessing it's at least as good as some of the designs that worked 150 years ago. I'll have to see. Maybe it won't catch anything. To Warsawdaddy, I haven't found anything by panning because I haven't tried it, but I have found some small pickers with a metal detector in the creek bank while relic hunting, so I'm guessing I may find more with the sluice. Hope so at least. Thanks for the reply.