Ok I have done some reading and got suitably freaked out about biofilm, white mould, chlorine gas inhalation etc etc! I have also run pipe cleaner through the tub, drained it and refilled it again, it’s now up to temperature and ready to start with new chemistry. I’m hopeful that we don’t need any more drastic decontamination procedures at this stage as we haven’t had any skin or health concerns and the tub is still fairly new (bought Oct 2020), with this being about our 3rd water change.
So my questions now are:
1) How do I gauge our chlorine demand when I was told not to worry a