Why am I getting this algae?

[PoolDoc]

Looks like mustard algae, which can be highly resistant to chlorine.

It will go away IF you raise the chlorine high enough AND brush it. With a CYA equal to 60 ppm, that means taking your chlorine to 20 ppm, and brushing while it's that high.

Also, it looks like your eyeball may be angled toward the surface. If you don't have a main drain, then it's quite possible you've accidentally created a no-circulation zone in your deep end. Ironically, the presence of algae in that location pretty much suggests your pool is not getting a lot of active use.

So, do this:
#1 - Run your pump 24/7 till the algae has been gone for 5 days.
#2 - If you don't have a main drain, adjust your eyeballs so that you get circular flow, angled down somewhat, throughout the pool. If you DO have a main drain, make sure the valve is open.
#3 - Raise your chlorine level to 20 ppm by adding bleach in the evening, and then brush the algae.
#4 - Hold the chlorine above 10 ppm for at least the next 5 days.
#5 - If your pump is on a timer, once you re-enable the timer, make sure to create TWO periods of circulation that total at least 8 hours together.

By the way, the 'BBB Method' doesn't preclude shocking -- as you'll see, we have shock doses listed in the 'Best Guess' chart! In late summer, with very hot water in many parts of the country, and with a summer's build up of algae fertilizer, higher than normal chlorine levels are needed.

Also, if you are testing with anything other than a Taylor based testkit . . . all bets are off, since we really don't know WHAT your pool levels are. (LaMotte makes a kit too, but it's over $200 retail and I haven't seen much evidence that they sell many of those.)