The submerged surface of the tub has just recently (last few days) developed a sticky feel.
The surface is textured but only recently have I noticed that I can no longer slide across a seat smoothly or rub my finger tip across the surface without feeling it "vibrate" as it alternately slides and sticks. The surfaces above the water line do not have this feel. Rubbing the surface with a relatively non-abrasive nylon pot cleaning pad seems to remove most of the sticky film.
I have a bit over three months on the water and posted the question "When to change water?" a few days ago. I mentioned persistent "islands" of large bubbles as the reason for the question.
Just analyzed the water and results are:
TCl = 0.5 - 3 (adjusted twice/day)
pH = 7.5 - 7.8 (adjusted down to 7.5 twice/month)
TA = 35 - 40
CH = 170
CYA = 0 (will try it next filling)
Borax = 40
TCl = 12-15 twice/month and filter washed
Typical load is two showered bathers/day for ca. 20 min.
Any thoughts about what is causing the sticky surface and more important, how best to clean it when the tub is drained?
350 gal Infinity using BBB