One good way I've cleaned my rocks that I've picked up out of rivers and off the side of the road is to hang the bucket in a tree in my yard. Then stick the garden hose in the bucket by the side of the rocks and just let it flow for a while, you will notice the water finally come clear. One of the larger ones I had to boil and repeat before the dirty stuff came off.
Oh and very very cool man. Looks great.
55gal Beginner FOWLR - 40lb Live Rock, 1 True Percula, 1 Sand Sifting CUC, 1 Scooter Blenny, 1 Sally LF Crab, 2 Turbo Snails, Frag Brain Coral, Tree Coral Frag, Zoanthid Colony