Thank you for the reply and clarity, it’s a great help. My CYA is high, according to my dealer, because of a cleaner I used in the tub to rid of a thick grease type stain they occurred above the waterline on initial fill and before the tub was used. One employee recommended the cleaner; however after using it, another told me it was not a good idea. TDS now at 1,200 and CYA is at 40 as a result.
I don’t mind using the lithium for now as opposed to bleach. I think I’ll continue on this path for the moment.
My PH now seems to have stabilized at about 7.5 however I do have some light scaling in the tub (fine sandy feeling on walls and seats that easily rubs off). I assume this is due to too high Calcium Hardness (CH) approx. 220. I need to drain my tub this weekend to bring down my TDS (before the really cold / freezing weather sets in – Canada), I anticipate this will also bring down my CH. When I refill I think I’ll aim start out with the following and see if I can keep my PH stabilized around 7.5: CH: 150; Al: 80; PH 7.5; and, CYA 40.
Thanks again for your invaluable input.