The only way i would say it to be worth it is depending on what that 50PPM is made up of. If it is made up of some oxidizing copper or other hazardous material to shrimp then i would say definitely. We have to remember though. The main reason we/I use R/O water for my shrimp only tank and soon to be my other tanks is because you know exactly what you are remineralizing the water with. Therefore you know 100% that it has exactly what you want in it and not what you don't want in it. You could just trial and error, although it can become expensive with crystal shrimp and TBs. But i think a good start would be to talk to your utility company and see what the water test readouts are and use your judgement.