plaster "polka dots"

[Jami]

We have built many pools over the years and just in the last 3 years we have had several get white "polka dots." It only happens on the colored pools. We think that it has to do with the amount of calcium in the plaster itself because we have checked the water from the taps at the houses and they all have had their chemicals properly balanced. Most of the customers use a very trusted pool service. Of course the plaster does not agree with us. Has anyone ever seen this before? Any suggestions?

[Grudy]

Jusy some thoughts.
- plaster/dye quality
- use of granular chemicals which settle on plaster
- low hardness levels in pool water
- inadequate waterproofing resulting in leaks which leech color