Will Tannin stain my Snails Shell?
 

So I re did my 10gallon and added new wood that i didnt pre soak. I like the look of tannins for the most part (I have to change the water every 4 days or so because it gets way to dark) but I noticed that my blue mystery snail, or apple snail, shell has become really dark. I didnt take him out to clean him or anything,

is this a sign he is not doing well in my water? or could it possibly be stained from the tannin. I have had him for a month or so and he has alot of new growth, but thats also a clearish color. Im thinking I may take him out and put him in a bowl with tank water and give him some tums every now and then for the calcium. I dont see him eat alot, he nibbles for a few mins on the wafers and pellets but dosent munch for hours like my other snails did.

I would be more concerned with the stocking if it is the same tank as the one you list in your sig...

To answer the question, no it will not harm your snails or fish, however if it is leeching a lot, then yes it is possible that it could stain the snails shell.

Tanks with heavy tannins also have dips in pH. You may want to check it, to make sure its not going so low as to hurt her shell.