hard water stains

How often would you say you clean your lids? I have a full coverage lid on my tank to prevent my wrasses from jumping, and it gets a decent amount of salt creep along the sides/rim so I clean it with vinegar and water at least once a month. If you do not have any lids how often do you clean your...

Hi everyone. Im cleaning my old aquarium to sell and there are these hard water stains above the water line left over after cleaning with razor blade. This is what I have tried: 1) vinegar soaked paper towels x 45 min - no change 2) Mr Clean sponge - no change 3) Soap/water - no change I...