I spread my $1.17 bags of Home Depot top soil on a blue plasruc tarp to dry. When dry, I shovel it into a Tote Tub soak it & stir it, pour off the water speed it back on the trap and repeat 3Xs.
After the last get out I run it through a screen.
I store until needed.
I've done this for several of my tanks and some for friends We've all had great success..
Clay, Potashm, Dolomite are added just prior to use. In somme mixes I add peat to organic like worm casings based on the plants.