I just switched mine over to sand Sunday night and I LOVE it. I emptied my whole tank (as I moved it to my new house 4 hours away from my old one). I put the sand in and then the water. I washed the sand very well the day before, so there was no cloudiness.
I washed my sand by filling buckets halfway then letting the hose run in the bucket until the water ran clear. I found that if you put your thumb over part of the nozzle to make the water pressure higher and point it directly into the sand, it speeds up the cleaning process. (But it starts to hurt your thumb... haha)