I'd go out and buy another 10 gal and split up the rock between two. There's no way you'll get decent flow in such a small tank with that much rock, unless you had at least 4 powerheads aiming at the rock from different directions. I had serious algae problems in my 10 while I had about 20lbs of figi rock; then I took out a couple of big pieces, with really improved the flow in all the areas in/around the rock. If you're saving the rock for a bigger tank, I think it will be better off for having the increased water flow around it.