My piece was a very large piece, can't remember exactly but around 40"x20"x28" maybe a lil bigger or smaller, that was new with no pre-soaking, with water changes and now that the tannins are starting to lessen a little, my ph is getting closer to 7 where i want it. i agree with above, if you are wanting to lower ph for long terms, the driftwood probably isn't gonna help much.