Gunite and startup half empty green and brown alge

I have a salt water gunite pool about 40k gallons. It is half empty already as we had to replace lights.
So my question is it simpler to just empty remaining water and scrub the walls and floor with bleach and refill since I haven't yet added any chemicals?

There is green and brown algae in the walls growing... water is murky but I can see about 4-5' down, not to 8' section though.

I'm thinking cost for original water fill was about $200. The cost and time commitment of 2x daily scrubbing walls and all the shocking that it may be more economical to just dump and scrub hard just once with bleach... I know do it quickly as not good to leave empty.

the current water ph is extremely high that it is off the charts and 0 levels of chlorine, very little salt content and the hardness level is only at 50 although so cold, who knows if it's correct?

So if I proceed with the empty and clean. What should be my first steps of adding chemicals?
I know I need CYA, salt, hardness, and ph minus as my normal chemicals. Do I instead just use bleach?


Thoughts?

Thanks so much. I already have a Taylor test kit....