here's a helpful site you may have seen:
http://www.petsforum.com/personal/tr...osalinity.html
from that page:
"The goal is to granularly reduce the salinity of the water to between 12 and 14ppt and leave it at that salinity for at least 4 weeks but preferably 6 weeks. Basically continue the treatment for at least 4 weeks after the last spots disappeared.
The salinity must be lowered gradually to give the fish time to adjust to the lower salinity and more importantly ensures the bacteria in the biological filter can adjust. It should take around 2 days to get from 35ppt to 14ppt.
Your starting point should be between 1.025 and 1.027. Replace about one fifth of the volume with
RO,
RO/
DI or aged freshwater that has been well aerated. Repeat this 12, 24 and 36 hours later, monitoring the specific gravity along the way. After the fourth water change the specific gravity should be 1.010 or pretty close. Wait a few hours to make the final adjustment to get down to 1.009. Note that you can estimate the resulting specific gravity. If you are changing one fifth of the water and the current specific gravity is 1.025 the result will be:"
FWIW I have a fish in 10g
qt now being treated with hypo, it took me about 2-3 days to get down to 1.010...problem being I got a refractometer and found I was actually at 1.014!! I am now down to 13ppt and just top off the tank every morning. Good thing is hypo allows biofiltration, I have some spare
lr in there and no worry of ammonia.