Calcium “dust” on the bottom of pool

[DryFly]

I just started getting a lot of calcium dust in a couple areas on the bottom of my pool. I’ve been using the Orenda calculator to balance the LSI. Here is the current chemistry:
Temp. 90*F
PH 7.4
TA 100
Calcium 520
CYA 60
Salt 3000
Borate 0
LSI -.05
I have had an issue with my SWCG increasing chlorine levels, but I believe I have that under control. I can get to a +.04 LSI by raising the PH to 7.5, but I don’t think that is the problem. Is this enough information ?Any thoughts on how to clear up this problem, and especially what I’m doing wrong to cause this, would be appreciated.