copper problem?

Alright, first I'll admit my ignorance...

I got a bunch of fish in the mail about a month ago that had ich the next morning. I tried a copper treatment, Quick Cure, which I understood would be safe for cherry and amano shrimp if not overdosed. I did not overdose, but a day or two later I put in another chemical that separated the copper compound and basically wiped out all of my shrimp in one night and most of the tetras over the next 2 week period (liver destruction, most likely) -- other fish survived.

It still bothers me to think about this, but after several water changes, I moved on -- according to my calculations I have less than 1% of the original water left. Got more tetras and shrimp. No problems with the new tetras (24 of them), but I am still losing a few shrimp per week -- I never lost a shrimp in the month before adding the copper.

My question: I pulled out some heavily rooted plants a few days ago and stirred up my ADA Aqua Soil quite a bit, and I did NOT do a water change at that time, which I regret. I have lost 3 or 4 shrimp since then. Would my substrate stay contaminated with copper for a long period? Or, can stirring up the substrate kill shrimp, if you are not careful?

My shrimp behavior was a little weird for a while after the substrate disruption ... lots of congregating, especially in the upper corner of my tank where the plumbing is. Today they are becoming more active again, but I did lose another amano last night. I have lost no fish during this time. If I should replace all of my substrate (I hope not!), I'll probably need to get a second tank and start from scratch.

 

One more question...

If you have no algae in your tank that the shrimp appear interested in eating, is there something you can feed them? I've been doing the rocks in the sun routine for the otos (and the snails inadvertently) and that seems to be working fine. But, the shrimp never go there.

 

I've heard that elsewhere. Luckily, I have not lost any shrimp in over a month, so I think that I'm OK. I dosed very lightly with the copper in the first place. I just got 11 Panda Corys which spend their days sucking off of the bottom, so if I have too much copper still, they will be the first to pay the price. Keeping my fingers crossed.