Getting rid of these water marks

[MrsFreshwater]

I've it big watermarks on my tank because it was second hand and I don't know how to get rid of it because I can't put and chemicals on it so what am I supposed to do???

 

[butterfly_koi]

The best and most effective method that I have found in terms of removing hard water stains is with vinegar, a razor blade, and a bit of elbow grease I keep vinegar in a spray bottle for this purpose. Just pour the vinegar on the spot, let it soak in a few seconds or so and scrape away! Good luck!

 

[tamtam]

Just like butterfly has said! I haven't come across much that vinegar and some work won't fix.

 

[bob mccoy]

it may sound funny but all my use tanks go in the bath tub . i fill it up and put 4 cups vinegar in and next morning it all wipes right off with ease. RINSE VERY WELL AND LET DRY VERY WELL !!!!!!!!!