High alkalinity, high chlorine (above 5.0) 7.4 PH -

[RLB]

Subject specs causing green algae build up on pool walls is various places.
Spots brushed daily but return in 1-3 days. Pool is 34 years old, water never drained. Water is clear, pumps runs 3 hours at night, filter recently backwashed and filtration aid added per specs.

Will shock treatment raise free chlorine level and take care of algae problem or does the chlorine level need to be brought down and then bring PH and alkalinity back into range?

[muss08]

To answer this I would need to know all your pool chemistry specs. These include Free Chlorine, Combined Chlorine (or total), pH, TA, and Cyanuric Acid. 7.4 pH is great but what is high TA? FC is okay if your CYA level is about 50. What do you use to add chlorine besides shock? Yes, shock will raise the FC and more than likely kill the algae but you need to keep the chlorine at shock level until it holds overnight (test at sundown and restest at sunup). This will ensure that all algae is dead. Simply shocking once may kill most of the algae but probably not all.