hi guys, i not sure is this the right place to ask but nevertheless...

recently i get an old aquarium tank from my fren, however it had water stains all over the aquarium which really irritates me. i had tried to use glass cleaner, car window cleaner and wipe it with newspaper but still no avail. i did some google and some recommend to try to use a lemon to clean it. but my fren said lemon will crack the glass( so acid meh the lemon??)...really nid help from sifus here to teach me how to remove those stubborn water stains