Operating a Sluice Box in Water
In a situation in which one must place a sluice in calm waters, you will find that is generally very difficult to reach the flux of water needed, because you will need to make the speed of water increase more than what it already is. If the current flux is not enough to move the material through the box, sometimes you will find that by changing the inclination of the box in the water it will not be useful at all in reaching the proper speed of water needed for the sluice.
For this situation there are some actions one could take in order to canalize a proper flux of water through the box so that the material moves at a production speed. Sometimes the flux of water of the same creek would be enough, so that by the structure of a “water director” in the creek, one will be able to move enough volumes of water so as to accomplish the expected goals. A water barrier or deflector can be built using piled up river rocks to detour the direction of water towards the sluice.
Sometimes one can reach water speed by placing a small water lift across the creek. By doing this and by placing the sluice in the place where water overflows, one can originate a more than enough water flux to comply with your needs. Actually, one does not need so much volume of water for a medium-sized sluice box to reach the required flux speed, if water is passed through the box with the right speed.
In the case of small lifts maybe it is necessary for the water lift to be enough to increase the fall of the box’s inclination to reach the right speed. How high should the lift be depends more than anything in how much water flows in the creek or brook.
A sheet or two of thin plastic or plastic tarp, or old rice sacks can come in hand when one is building a lift or a water director within the creek. These materials help prevent water to filter through the cracks in rocks.
A water director or elevator can be generally used with good results when waters flow and it is not that deep so that the construction of a barrier based on rocks becomes difficult to build. If water in the working site flows too slowly or for some reason the construction of a lift or water director is not possible in the place, it will be necessary to either build a sluice in another place where water flows faster or use a water pump to suction water directly from the sluice, or in other opportunities it is possible for the siphon water in the box from a higher point upward stream.
Siphoning can be effectively done with a reinforced garden hose or some other types of heavy walled water hose or PVC.