so many variations mate, sluice width, riffle height, minersmoss v ribb, gold hog matt, carpet. just depend on how much water you need to flush your system through and how effective your riffles are, what angle you run at. You can never have a one size fits all due to the varying conditions i.e. sediment level, ironstone, leadshot etc. Min I would run on any 300mm wide sluice would be 3700GPH