Keep in mind that, unless you have a laboratory certified/professionally calibrated hygrometer (the kind you get from a laboratory supply house), the accuracy will be +/- several percent RH. So, even though you *think* that you are at 65% you may actually be at 62% or 68% or anywhere in between. Typically, this shouldn't present a problem but it is helpful to keep that in mind. (For what it's worth, I use a professionally certified hygrometer and have my humidor dialed-in at around 65%-66%, give or take).