FYI, I wouldn't remove any molted carapaces. Even if a corpse has died, I usually leave them in for 24 hours or so. This gives the survivors time to pick off any bits that they want, and it will not foul the water in that short of time.
All of the shrimp that die on my tanks end up as fodder for my crayfish. They can chow down a full grown Macrobrachium dayanum (3") shrimp in about a minute or two.
Good luck with your salwasi (sp) shrimp.