Using hyposalinity therapy is a simple matter of lowering the salinity in fish-only systems without live rock. Since invertebrates, live rock, and live sand should not be exposed to such low specific gravity, the fish must be moved to a conditioned hospital tank for treatment. Filling the quarantine tank with water from the display reduces transfer stress. Begin to lower the salinity the day after the move. The salinity should be adjusted downward using four water changes over two days' time. Each water change should lower the salinity about five points. The salinity should be kept consistently at 14ppt for three weeks or more. Bring the salinity back to normal over a period of about a week at two points per day after completion of therapy. It is important to measure the salinity daily with an accurate hydrometer or other refractometer. Allowing the salinity to rise during therapy can result in reinfection. Many glass and plastic hydrometers can be inaccurate.