So your water supply contains chloramine. Your dechlorinator will split this into chlorine and ammonia then remove the chlorine. Depending on exactly which brand you use, it may or may not also contain something to detoxify the ammonia part.
As has been said before, plants could well be treated with a chemical to kill snails.
Several years ago, one species of apple snail was found in a river in Spain, so the EU, operating a one size fits all policy, banned the import and spreading of all apple snails in every EU country. They were also intending to ban the import of plants from any country where they could have been contaminated with apple snails but finally passed legislation that imports of plants would be allowed provided they were treated with a snail killer. This basically means that any plant imported from any country outside the EU has to be treated. These snail killing chemicals don't seem to affect MTS or any of the 'pest' snails though, but they do also kill shrimps.
The way to deal with such plants is to quarantine them, do lots of water changes and run a carbon containing filter in the quarantine tank.
I doubt whether any chemical residue on the snails is enough to kill shrimps, though the slight possibility does exist.
When I first got my cherry shrimps, they all died. The second batch all died as well. But before the last one died, a shrimp expert helped me, and told me why they were dying. The last one was a berried female; I put her in my quarantine tank where she died, but not until after the eggs hatched. All the baby shrimps survived and formed the basis of my shrimps colony.
All the dead shrimps had a white line across their backs which indicated to the shrimp expert what the problem was. This is why I asked what your shrimps were like, in case it may the same cause.
As has been said before, plants could well be treated with a chemical to kill snails.
Several years ago, one species of apple snail was found in a river in Spain, so the EU, operating a one size fits all policy, banned the import and spreading of all apple snails in every EU country. They were also intending to ban the import of plants from any country where they could have been contaminated with apple snails but finally passed legislation that imports of plants would be allowed provided they were treated with a snail killer. This basically means that any plant imported from any country outside the EU has to be treated. These snail killing chemicals don't seem to affect MTS or any of the 'pest' snails though, but they do also kill shrimps.
The way to deal with such plants is to quarantine them, do lots of water changes and run a carbon containing filter in the quarantine tank.
I doubt whether any chemical residue on the snails is enough to kill shrimps, though the slight possibility does exist.
When I first got my cherry shrimps, they all died. The second batch all died as well. But before the last one died, a shrimp expert helped me, and told me why they were dying. The last one was a berried female; I put her in my quarantine tank where she died, but not until after the eggs hatched. All the baby shrimps survived and formed the basis of my shrimps colony.
All the dead shrimps had a white line across their backs which indicated to the shrimp expert what the problem was. This is why I asked what your shrimps were like, in case it may the same cause.