How to remove eco-earth stains from shells?

[Xenpurgisnachtt]

Title explains it pretty well, does anyone know how to remove eco-earth coloration stains from shells? I've tried basically everything at this point!

[aussieJJDude]

Once it's stained, unfortunately theres real no safe way for the crabs.

(Its also one of the reasons why many encourage not to use EE, since it does stain shells!)

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[wodesorel]

Soaking in a bit of hydrogen peroxide is the only thing I can think of that might work, but I'm not sure if it would cause any damage to the finish of the shells. You might want to test one just to see. Peroxide is unstable and breaks apart into plain water extremely quickly, so it wouldn't leave any residue behind once the shells have been rinsed and soaked in water for a few minutes. It's commonly used in active aquariums to deal with unwanted algae blooms and stains.

Edited to add: commercial shells are bleached to remove smell and any organic bits left in them. It too will break down rapidly, and when soaked and rinsed a few times and allowed to dry will not leave residue. A final soak in heavily dechlored water is a way to be certain there is none left. Again, there could be damage done to the shells so a test is needed first.