Hypo can be very effective for some parasites, but not all. Same can be said for any treatment out there. There is no one treatment does all. Hypo is effective on the most common strains of ich and the most common flukes that one comes across in the hobby. To be effective, the s.g. must be maintained between 1.009 to 1.010 for 4 weeks, and measured daily with a lab grade hydrometer, refractometer or conductivity meter. In general for new fish, I recommend quarantining for at least 6 weeks and treating as necessary for anything you observe using a specific treatment known to be effective for what ever happens to show up during QT.