Your cleaner shrimp molted every week or so?? Really? That's not typical. What is typical is for the shrimp to hide several days after a molt, as their shell is still soft. Sounds like you had a defective shrimp from the start.
I wouldn't worry about copper, you have other inverts that are fine. Don't add more stuff for a while, get good at keeping what you've got, them build on it.
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Brad
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