I'm getting a build-up of a white substance in my skimmer, in particular building up on the thermometer and any items that may be in the basket (ie leaves). It is very thick, has the exact look and consistency of mucous, and is not the usual crud that builds up in hot tub skimmers.
This is actually my second occurance; the first was two weeks ago in a 10,000L indoor hot tub (concrete/tile, sand filter). The second is now in a 5,000L outdoor hot tub (concrete/tile, sand filter). Both are maintained in the neighbourhood of 7.5/130, 3-5ppm FC, but the FC occasionally drops to near 0 or goes up to 10 if usage is misjudged.
This is what happened at the first tub:
For a week and a half, I was cleaning it all off and did a mild shock (10ppm) a couple of times. It continued to grow back, so I triple-shocked the hot tub (600g Cal Hypo in 10,000L) for five hours. Afterwards, I drained, scrubbed the surfaces and skimmers, used a pipe cleaning product (Swirl Away), and used a filter cleaning agent (BioGuard Filter Brite). However, I think it may still be coming back; will know for sure in another week.
I am hoping someone here has some idea on what this is. The local health authority has apparently never heard of/seen anything like it. Nor has any of the three pool stores I have visited (including my main supplier); a rep from BioGuard suggested it was a bacterial colony, hence the attempted treatment mentioned above. I am also worried that I transferred this into the second tub on my own hands, despite some serious hand washing and scrubbing.