Originally Posted by Wayne Dwops
but is the ph and gh going to go down too low to be cherry shrimp safe?
pH swings as a result of injecting CO2 are not harmful.
Injecting CO2 will not lower gH.
As mentioned, the Hagen CO2 system you linked above is just a fancy DIY package (you can make DIY CO2 yourself, if you do not want to use pressurized CO2).