best way to remove calcium buildup?

[burrier]

what will help remove this but not kill fish?

 

[haynchinook334]

Fine grit sand paper, 1000 grit. or a razor blade.

 

[Lupin]

Fine grit sand paper, 1000 grit. or a razor blade.

 

[Camshaft Ramrod]

As long as it's an empty tank, I use PH Down. It's acidity eats away the calcium. It's quick and easy.
Just rinse when you're done.

 

[burrier]

ok thanks!