I just recently drained cleaned and refilled my HS tub, pretty much they same way I have for many years now with no issues until now. First some info on my tub, it's a HS Vanguard and I use chlorine to shock and treat, also Nature2 spa stick sanitizer and that's it. My water I use to fill the spa is pretty soft and low in minerals, I test it yearly at Ward Labs and use it for brewing beer. I've never used a filter attached to the garden hose when adding water after a draining. I've always use some type of spa system flush before draining, this year I used SeaKlear. And I always use metal gone when filling back up, then a bottle of ph balance, and a new Nature2 stick.
Now my problem that I'm seeing after the first time draining this year was a black sticky residue around the water line were the foam from spa flush was, and it was extremely hard to remove (several magic erasers). After filling the water was crystal clear but a lot of white flecks floating and also some brown streaks that would accumulate along the high edges in the spa under the water? I could easily wipe the clear, but come back the next couple days and they would be back. I tried raising my chlorine levels, but it didn't seem to help. Took sample of water to be tested and everything look good, except a high phosphate level. I suspected as much since I think I didn't rinse the tub well enough and I had some foaming when starting the spa back up for the first time.
Drained tub rinsed thoroughly and refilled, the white specs/flecks are gone but I still have the brown streaks.
Any help or ideas would be greatly appreciated, thanks.