Planted Tank Guru
Join Date: Jul 2010
Location: Huntington Beach, CA, USA
You may/may not need the vinegar. Depends on how the scale goes. Lots of the hard water mark will be limestone. That is alkaline so adding vinegar, which is a weak acid tends to cut and loosen the scale. With a razor blade scraper, you may not need the vinegar if you keep livestock who might suffer from just a bit of weak acid in the water. A good water change will also reduce the effect if some does drip into the tank.