I have algae again! What am I doing wrong?

[Aggiechica]

So I posted on here and slammed my pool for the first time in late July after draining and replacing 70% of water because CYA was so high. It was crystal clear and beautiful for a couple weeks, then I noticed algae a couple weeks ago. So I slammed again. Looked pretty good and made sure to test pH and chlorine daily. I'm starting to see some algae again! I'll post pictures from my phone. I did the whole set of testing this evening:
FC: 4.0
CC: 0.5
TC: 4.5
pH: 8.0 (I have a hard time figuring out exactly where the pH falls by the colors, so any tips here would be great)
TA: 70
CH: 125
CYA: 40
CSI: -0.10

I added liquid chlorine and muriatic acid to get FC and pH to recommended levels. But I guess I need to SLAM again? Any insight on why the algae keeps coming back?

Also, my bag of ice melt finally came, so I need to add that to get the CH up to recommended range. Should I do that tomorrow? Or wait until the SLAM is done?

 

[Aggiechica]

These pictures were taken at night with the pool light on. The color seems way more green on here than it actually is.

The first pic shows a little bit of algae on the floor of the pool.

Second pic is on the side of the ledge in the deep end, where I see the most algae. (When we bought the house in the fall, we knew we are going to have to resurface the pool, just wanted to get at least a summer of swimming in so we can decide what we want exactly. )

 

[HermanTX]

There are several things to consider.
After your first algae breakout, did you complete the SLAM and meet the criteria such as the Overnight Chlorine Loss Test
Could you have some lingering algae behind a light or on a ladder, even pool toys?
I see you FC of 4ppm which is not exactly in the recommended range for 40 CYA. The target is 5-7 with absolute minimum of 3. In the summer I run my FC to top of range and not sit on the ledge of minimum. It is just too risky if for some reason I miss adding LC, or and very hot/UV day, etc.
I add my LC twice a day - once in morning then in afternoon/evening. This keeps more consistent level of FC in the water. I have had to batch treat on a long weekend away but I supplement that with pucks in floater to avoid any drop below the lower range value

 

[Bperry]

If you have algae growing. It means there’s not enough chlorine in the water.