What kind of test kits are you using? If you don't see ammonia or nitrItes from the shrimp (should show up around day 4-7, or so), you may already have a colony of bacteria that is already converting them. The nitrAtes should be showing up, I wouldn't worry about the pH yet either. Can you get your LFS
to test your water, just to confirm?
By the way, damsels can be pretty nasty to new tank mates once they have established their territories.