Yeah definitely rinse it good.
I did probably 15-20 pounds at a time. Poured it in a 5 gal bucket, filled it up w/a hose pipe and stirred the crap out of it. I used the hose nozzle in my hand to stir as it was filling up. Pour the water out, and repeat. Did this 2-3 times for each batch. The water will get subsequently clearer with each rinse.
There may be a better way, lol. I used 125 lbs in a 75. It was pretty clean when I filled the tank. Cloudy of course, but it quickly cleared up.