Zodiac Ei2 expert chlorinator help please

[Todge1]

I have recently installed the above chlorinator having replaced the old unit which became defective ( and it was old).
Since then I cannot balance the water correctly.
It is now clear but there are brown stains on the render. Water is also not as blue as normal, it has a green tinge. Render is dark grey so normally we have a lovely blue colour
The PH is 7.4 but the TDS / PPM is 3600 . I believe the guideline is not over 2000.
I understand I need to back wash several times but what is unclear is whether the chlorinator should be set at 100% or should I reduce the chore production ? Water temperature is currently 30 degrees c, the zodiac machine does not actually give any readings of the salt level which seems bizarre.
Thanks for any advice