A method that I have used for many, many years is to use a cylindrical plastic conainer large enough to hold several reels. In the bottom are drilled a few very small holes. I insert the reels and fill the container once and then pour out the water to remove any fixer trapped in the reels. Then I adjust the water flow so that the container remains filled with water and little spills over. Clean water enters at the top and water and fixer exits the bottom. The size and number of holes are adjusted so that once filled the container will drain in approximately 1 minute when no additional water is added. I leave the container under the tap for 20 minutes. Since the flow rate is quit small I feel this method conserves water while providing good washing. I have negatives that are 50 years old that show no problems from residual fixer. The diameter of the container should be small enough so that the reels do not move around but remain on top of each other.