Calcium deposits?

[halefmly]

Is this a calcium deposit? (see attached photo).

Before I was introduced to this site, I used Cal Hypo to deal with an algae problem. I have since been testing regularly, keeping chlorine levels up with my SWCG and pH and alk balanced with muriatic acid. I have had the pool open for 10 months, and had some growing pains with the SWCG, but seem to have a good balance now.

My numbers this morning were:
FC: 9.0
CC: 0.5
TC: 9.5
pH: 8.2
Alk: 130 (I have since added 1 gal muriatic acid-will retest in a couple hours)
Cal: 420
Cya: 60
Temp: 78
Salt: 3200

My typical readings throughout August were:
FC: 8.0
CC: 0.5
pH: 7.8
Alk: 100
Cal: 420
Cya: 65
Temp: 83
Salt: 3200

Can anyone tell me just what the build-up is (in the photo) and how I should remove it?

Thanks,
Larry