What sanitizer are you using? If you're using biguanide (e.g., BaquaSpa, SoftSwim) this a fairly normal phenomenom and nothing to be concerned about. BaquaSpa sanitizer (and probably the other biguanide spa and pool sanitizers) seem to contain a little surfactant (i.e., detergent or related compound) that tends to make things feel a little slippery. The surfactant is there to help minimize the buildup of scummy biguanide deposits at the waterline. It also accounts for the tendency of BaquaSpa-treated spas to turn milky white when the pumps are on high with air injection. This is due to millions of micro-bubbles produced by the injected air and facilitated by the surfactant.
A lot of people really like the silky feel of biguanide-treated spa water. I used BaquaSpafor a couple of years but finally switched to chlorine.
Don
We use Nature 2, add chlorine once a week and shock weekly on a different day (per the dealers instructions). With this sanitizer, do you think we have nothing to be concerned with?