Used a brass check valve, didn't go well.

[Clooney]

So... I used a brass check valve without thinking on my tank, it was only in for about 5-7 days at most but I lost all my softies (only type of coral I had), cleaner shrimp and some snails. I've been reading around the Internet and there's a lot of people saying that I need to replace everything because the copper sinks into the glass and all my equipment including the rock and sand. The valve wasn't on for long so I'm wondering am I safe? Will I be ok with cleaning everything and doing many water changes? I can't afford to replace my whole tank.