...If I lower the water level a few inches below the deposits, take care not to drip vinegar into the tank, and wipe of the exess vinegar with a wet cloth when I'm done?
Try very fine steel wool. It wont scratch your glass.You can buy it at supermarkets/ Bunnings. Look for xxxx fine, the more x's the finer it is. It will also remove the most stubborn algae. Its commonly used for french polishing.