Do a 100% WC with tap, if that's what you're using, in the low tech tank and treat with Prime. Do you have any snails you can move into the low tech tank, like nerites, ramshorns or mysteries to be an ammonia source? If so, move a few. If not, move a fish or two. Wait a day or two, test for ammonia, nitrites and nitrates to make sure the tank is totally cycled.
Check the pH, GH and KH of the CO2 tank and compare it to the low tech tank. The more different the params are, the longer you'll need to drip acclimate the shrimp. Or try this method from planetinverts.com
http://www.planetinverts.com/Acclimating New Shrimp.html
-Lisa