Granular flow in submerged hoppers show is used to study grain – liquid interactions. The superficial velocity of fluid is faster than the grains’ leading to counter intuitive fluid-is-faster effect even if the potential energy of the grains drive the system. The effect can be illustrated by inserting a layer of dye on top of the granular pile and observing that it exits before the grains run out. If the grain and fluid velocities would be the same, the dye and grains would exit at the same order, dye after the grains, as this was the initial configuration.