George,
I would be a bit suspicious of your CO2... theres an online calculator many of us use, and that shows that your CO2 levels are way too high. However, I would expect not just shrimp deaths at that level, but lots of fish deaths as well.
Heres a link to the calculator.
Also, is there any reason why you bubble at such a high rate? How large is your tank? What do you use to dissolve the CO2? Why did you set your KH so high...i.e. what are you planning to keep?
Bookmarks