Thanks,
I was hoping they wouldn't get eaten

right now both the puffers and loaches are too small to eat the shrimp. Some people on the dwarf puffer forum have reported success keeping shrimp in the same tank...
I'll definitely check into getting more CO2, it seemed from the pH, KH and CO2 charts that it was up around 30ppm but I don't have expernsive test kits and they may not be super accurate.
Irene