IMHO you're just better off transferring your livestock to the newly set up 10 gallon with a little newly cured live rock in it seeded by some sand from your 5 gallon. Then you can bomb the 5 gallon with about a cup of kalwasser (pickling lime) and keep water movement on the 5 gallon for about a day. After a day of bombing with the pickling lime you can take out all water from the 5 gallon, then put in completely new water and start the curing process. A previous poster on this thread miss typed and said that the higher PH makes the water more acidic, it's the opposite, it makes it more basic and will kill off all inhabitants when you bomb the 5 gallon (so make sure that there is nothing in the tank or on the rocks that you want kept alive, if so frag it and get it out of there before you bomb it!) If you have any larger aptasia most peppermints won't even touch them, peppermints are better off used when you have killed off all of the adult aptasia and want to make sure that aptasia doesn't get a chance to grow back. So make sure you have some peppermints in your 10 gallon so that you can keep the aptasia under control. In most cases where I have seen aptasia go crazy it is from overfeeding, so make sure that you aren't dumping large amounts of food into the tank.