We don't actually support stand alone hot tubs here.

Operating them is equivalent, approximately, to operating a very high load indoor commercial pool, with a poor ventilation system and a weak cartridge filter system. Doing so is very, very different than operating an uncovered outdoor home (= low load per gallon) pool exposed to UV light (= enhanced oxidation).

The tissue stuff sounds like a major infestation of biofilm. Cleaning that up is NOT something you can do with normal BBB levels. Having the Taylor kit will allow you to take levels to the maximum shock level, and keep them there, which is needed to clear biofilms.

But I'll ask Chem_Geek and Waterbear to take a look.