Hyposalinity question - QT tank - how fast can you lower SG?

[howdy20012002]

i have dropped salinity over a very short period of time without any problems..(over a 1 hour period.)
i have been told that going down in salinity isn't a problem.
going back up is should be down much slower. (i myself have done it over a few hours without a problem)
just what I have heard and praticed.
for medications, I swear that I have lost more fish trying to treat ich with meds that the ich itself would have killed.
from the reading that I have done, Hyposalinity is the recommended way for quarantining fish and is proven to reduce death and stress on the fish

hope this helps
Neal