Cleaner shrimp died???

[martym]

My cleaner shrimp died, nitrates >5ppm sg 1.0225, Alk- 13dkh, calcium 320ppm, ammonia 0, Temp 81 Any ideas? Up until it was lying dead, it seemed healthy. Everthing else seems ok except for xenias, they aren't looking very good. They have been that way for afew days. Added a new yellow tang today, a orange poly and a leather a couple of day ago. Been having a hard time keeping calcium up, so I have been adding turbo calcium. Any help would be great before more things die, have I over looked something?
Thanks