Crabs etc and Soda Water

[gregzz4]

Feb 2nd I bought my live rock and started curing it. Since then, every water change, I have noticed my brittle star population dwindling and losing legs. So, time to catch some crabs. I have at least one ( what I think is a ) Porcelain that I'd like the LFS to ID, but I see one guy with hairy spotted legs, and another I took in yesterday with big claws. He became Mantis food @ J&L.
The wife brought me home some soda water tonight as everywhere I went didn't carry any. Can you believe that? Esso, Chevron, 7-11 ... no mix.
Anyway, I plan on putting my curing rocks into a bucket and squirt some of the soda into the holes with a baster. I tried sitting the rocks in the dark in an empty bucket, but no go. I don't want to keep doing this as the rocks are almost finished curing.
So, lets see tomorrow how some Co2 works

Anyone have any other ideas? Keep in mind the rocks are in a rubbermaid ( covered ), so a trap won't work too well.