have you used any real big piecesI would give it a good wash, then throw it in your tank. I have used all kinds of found drift wood and found them all to be safe. Don't put it in any tanks with really sensitive fish at first, but otherwise go nuts. Just my opinion of course.
is a soft wood . how long before the rot and are doneit could take years for it to stay submerged being that size. if it came from the lions bay area, chances are it is some sort of softwood species as that grows wild along the shore and up on the mountain, cedar, fir, spruce, perhaps cottonwood, maybe alder which is considered a hardwood by the "wood folks" but actually it is a very soft hardwood. I have collected a bunch of driftwood from Harrison lake for my freshwater tank...I am sure some of it is cedar, but other branches are heavier and harder. I have had them sitting in a bathtub full of water for 4 weeks now and they are not even close to staying submerged with the exception of 3 pieces which are 90% submerged!