Thank you Tom, I di go through the wash cycle with three bags for the 125 gallon some years ago. It was a huge project. As you say, time was cheap for me. The one thing I did not do was sort through the rock for the different materials. I guess I was either extremely lucky, or did not have that tank running long enough to have anything break down on me.
Maybe just as well to go ahead and spend the money right off the start and not worry about the sorting. My eyes are not what they were 12 years ago when I did it.