Great job on reaching day 10. I don't believe you should worry about gaining a pound. I am on day 13 and have experienced days weight loss and gain. This morning I lost 2 lbs over yesterday but was at the same weight the previous 3 days. I have lost a total of 16.5 lbs as of this morning. In regards to the SWF. I have used the SWF (Salt-Water-Flush) every morning of this fast. I do not believe at least in my situation that it has caused me to gain weight.
Although keep in mind that a quart (32oz) of water weighs somewhere in the neighborhood of 2+ lbs. So if you weigh in after drinking the solution you will weigh more than when you first wake. If you believe that you are retaining the solution in some capacity then maybe you need to adjust the amount of salt as the book suggests. The one difference between doing the SWF (Salt-Water-Flush) and sticking only to the lax tea is that the SWF (Salt-Water-Flush) actually is flushing through your system, washing out anything that is just hanging around. I do not believe that the lax tea has that capability. Good luck with your fast.