Shells

Question
Is there any reason not to put the shell of a saltwater critter into the guppy tank? It's a conch shell that I found underwater, so it has no lacquer or other decorative coating.

Answer
Dear Janet,
Shells added to a freshwater tank will affect the hardness and ph of the water. Don't add too many and just be sure to check you ph and hardness regulary with a test kit to make sure it is still in the best range for guppies.  
Hope this helps!
Karen