Help---SW snails die when I add them in

Question
I have a 125 gallon sw fish tank, all parameters are fine, I have shrimp tangs, angels, etc when I add star fish or snails they immediately die, I cannot figure out why.

I have check all parameters, the cleaner shrimp don't die and they are sensitive as well.  the water tests clean for copper can there be something in the substrate or decorations?  What can cause snails to die the same day I add them in?

Answer
Hi Diego,

    This is a tough one. The only thing I can think of is a high nitrate level. Usually this will affect shrimp too, but if it has risen over a period of time and your creatures in the tank have become acclaimated they could, conceivably, survive. Introducing new livestock, however could have a very different effect because they are coming from a relatively nitrate free environment. The difference may be too great to overcome, even though the rest of your readings are okay. Check your nitrate level and let me know how you make out. thanks, gerry.