Removing Hard Water Stains From Active Tank

twood

Member
Somehow I have gotten a whitish film on my tank glass. The tank is only a year old and was purchased brand new. It appears to be calcium or hard water. I have tried using my MagFloat, an algae scrubber pad, and a razor blade to remove it. It won't come off. This tank is in use and I don't want to tear it down. Any idea of how to remove this without tearing down the tank?
 
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