Descaling a cold water container in the bathroom

[superal]

The cold water that is within a tiled enclosure about 1 meter x 1 meter deep x 40 centimeters wide is heavily stained by limescale .  It is coloured brown in some places and the thickness of an eggshell . I have tried several ways to remove it including vinegar , lemon , toilet cleaner with 14% hydrochloric acid and finally scraping with a decorators scraper and a Stanley knife blade but all to no avail . The Stanley blade did remove some scale buy took ages and the blade became blunt .

Has anyone managed to achieve success in descaling similar to above ? tips would be welcome   

[brianthainess]

Did you try vinegar and lemon mixed together ? the two different acids work together. it will remove rust stains on tiles so give it a try.