I am certainly not an expert but my understanding is that for hyposalinity treatment you need to drop your salinity slowly to 1.009 over a period of 48 hours, I do not know what dropping it in a few hours would do but I would think it would stress the fish out a lot, 1.010 will kill the Ich but 1.009 is still safe for fish but gives you a little buffer for evaporation, I have heard it recommended to leave QT tank at 1.009 for a month after all signs of Ich are gone, then slowly raise it back. It is correct that this must be done in a QT tank or a tank without live rock, sand and inverts. If you do a search on Hyposalinity you will find many threads on it, Find one that tells you how to do it from one of the sharks.