Adding Journals

Hello SuSE folk, Don't know why, been that way a long time ! Have several partitions. Some are ext2 some are ext3. Want to convert hdb5 and hdb8 from ext2 to ext3. Command is something like "tune 2fs -j /dev/hdb5 hdb8" ??? Is that correct?, And should those partitions be unmounted when that is done? Thanks for the guidance folks. Bob S.