help green algae

I have been trying to get green algae to clear up for some time. Tried just about everything.
Free chlorine is 7.3ppm
total chlorine 7.3ppm
combined chlorine 0.0
ph 7.7
hardness 210ppm
Alkalinity 0ppm
cyanuric acid 90ppm
copper .04ppm
iron .09
My pool is 15000 gals. The pool store said alkalinity is 0ppm which I get that it is 120ppm on my test strip and the other pool store said yesterday it was fine. They gave me 4 gals of liquid shock in gal jugs and a bottle of algae control 60 by pool season. they told me to put half the algae control 60 in 32 oz. bottle. I am not sure how strong the liquid shock is as I can put my nose up to it and not have a problem smelling it. We pulled the stairs out today and they had algae on them, we cleaned them and left them out of the pool also changed the sand in the filter to and fixed the crank in the filter also. I'd like to add a picture but not sure how to.