White dust in pool when brushing

[Gottabewet]

We just completed a 2 week slam for what may have been mustard algae. We were very active and monitored the pool hourly throughout this 2 weeks. It was a war and I felt we won. Pool was beautifully clear for 2 days. Now there is a clear/white dust that stirs up from plaster when brushing. Pool is clear and pretty 3 hours after brushing and vacuuming.

PH -7.3
CH 600 (prior to slam 450)
TA-120
CYA-70
FC-7
CC-0
CSI is -0.02

What could this be? What could make the calcium go up? Do we need to remove and replace some water?

 

[JohnT]

What source of chlorine did you use for the SLAM?

 

[Gottabewet]

Pool Essential and Kem-tek Liquid Chlorine 10% from Lowes.

 

[JamesW]

Is the pool painted?

If you rub your hand on the surface, does it leave white residue on your hand?

 

[Gottabewet]

No it is a 1 year old DiamondBrite plaster finished pool. The pool floor seems to have more clear/white dust come off when brushing. I rubbed my hand on both the floor and the walls and nothing came off in my hand. It's not a huge dust cloud but definitely noticeable.

 

[JamesW]

Maybe dead algae or calcium carbonate.
Did you use any calcium hypochlorite?
Did the pH go high at any point?
What filter do you have?
If you have a sand filter, what does the backwash water look like?
If you have a cartridge or DE filter, you should open it and clean it well.
Brush daily, vacuum as needed and maintain good chemistry and the problem should go away.