Likewise, how do I remove limescale from my fish tank?
Remove limescale (white residue) from your fish tank with white vinegar, which is a weak organic acid and safe for use in aquariums. The vinegar (acetic acid) will dissolve the limescale (calcium or magnesium carbonate) seeing that it can be dissolved by any acid.
Besides, how do I get the white stuff off my fish tank?
Lay the tank down on a towel, and pour enough vinegar on the affected glass to cover it. Let it sit for 10 to 20 minutes, then scrub with a non-abrasive pad or cloth. If you have a stubborn patch of build-up, try using a razor blade or algae scraper to gently scrape the scale away from only glass panels.