Crabs, Snails, Shrimp, ALL DEAD!!! Help!

[wildbunch]

Algae is starting to get to be a pain. Would like to get another cleaner package but my last one from Saltwaterfish.com has only 2 Astrea Snails left. 18 Astrea Snails, 25 Blue Legs, 20 Red legs, 2 green crabs, camel shrimp, 7 Turbo Snails are ALL DEAD!
I purchased the biggest Red Hermit crab I have ever seen, 3" out of the shell. He lasted one night. Saw him running out of his shell across the sand before going to bed. After the big red hermit died off I realized half of the Invert package was gone so I took out the eel. I used to have a Snowflake Eel in but figured he was the one eating the Crabs so I put him in my other tank.
175 Gallon Tank inhabitants: 4" Juv. Emporer; 7" Naso; 3" Cinnammon Clown; 3" Bi-color Angel; 2 Blue Damsels.
The remainging cleaner package slowly died off. Just recently tried to put a Mexican Turbo Snail in, he lasted about 4 days.
Does anyone have any Idea why they all keep dying? My two remaining Astrea snails have been in there about 6 months.
Tank Chemistry: PH=8.2; Ammonia=0; Nitrites=0; NITRATES= 50 PPM; Calcium=?; Phosphates=?;
Any help would be greatly appreciated.

 

[dave espi]

well ya probably rushed the acclimation process... or did ya simply plop them in ?

 

[jonthefb]

yeah how did you aclimate them all? any big swings in water params or templately? how about the emperor angel ever seen him be nippy?
good luck
jon

 

[dreeves]

Have you ever used a copper in your tank, or any items in your tank which may have been exposed to copper? Have you tested your supply for copper?
Long shot of course.

 

[beth]

Nitrates are too high for inverts. Add some macroalgae instead of a cleanup crew. It will take care of you nitrates and nuissance algae.

 

[buzz]

Thought I was losing my mind for a second...you posted this under the Fish Discussion forum as well...I replied there...then I looked here, and saw a whole different set of replies...although mine was pretty much the same as Beth's.