Ok this is how I did mine yesterday.
Grabbed, from my wife, one of those 45 qt storage bins. Its about 18x18x7, I figured it would be easier if i could wash more surface area at a time and not have the sand be to deep. I was able to drop an entire 50 lb bag inside.
1st step was to run the hose into the sand spraying it down and letting it overflow. Every 5 minutes or so I'd lift it up on one end and drain it and then let it fill and overflow again.
When most of the darkest colors were gone I'd add 2 2x4 blocks underneath one side to give it tilt.I then proceeded to spraying the sand and letting the overflow run off.Once the overflow statrted running clear, I turned the bin around and sprayed again and let it overflow. You'll notice the water get dirty as hell looking again, its ok it clears up. Once you get it running clear you are good to go.
I'd do this a couple of times maybe in all 4 directions. I only did it from 2 sides and in 12 hrs I still have cloudy water. I started my XP3 this morning, filled with nothing but poly fiber to help catch the finer particles that I might not have gotten.