Balloon rams will be over bred and possibly have weak immune systems and be prone to health issues.
Rams are a fairly short lived cichlids at the best of times.
They may well have been bred in harder water. If they are thriving at the local fish store it does not prove that they will thrive long term. Some problems will take a little time to manifest.
If you like rams but have hard water, I would suggest you look at bolivian rams.
They are much more hardy than ramerizi and tolerate a far greater range of pH hardness and temperature.