Algae or something else?

[Buge]

Hey TFP, I need some help from the experts! I opened my pool this past Saturday. Pool wasn’t very dirty but I did the SLAM process to get my water clear and algae free (or so I’m hoping). The water cleared up and I did pass the overnight chlorine loss test yesterday. There were no visible signs of algae so I stopped the SLAM. Now I’m having this black dirt/dust looking substance on my sun deck. I have attached photos for reference. The substance is easily brushed away but it comes back after a half day or so. I’m not able to pick it up as it dilutes into the water. Is this algae or something else?
Water test results as of tonight-
Free Chlorine - 14 (Still coming down from SLAM)
Combined Chlorine - Less than .5 (Hardly tinted pink with 10Ml sample)
PH - 7.4
Alkalinity - 100
Calcium Hardness - 200
CYA - 60
Temp 83 degrees

Thanks!

 

[TinFoilHat]

Did you clean or backwash your filter after the slam? Did you clean everything in the pool inside and out with high chlorine water? Do you have a high level of pollen falling around you?

 

[Buge]

I do have a ton of pollen falling into the pool and I scrubbed the pool multiple times. I did not clean my cartridge filter after the SLAM process. I will do that tomorrow to see if it helps.

 

[TinFoilHat]

Then I think what you're seeing now is the pollen, but do at least clean your filter.

 

[PoolStored]

Looks like dirt and organic debris, not algae.