Hi,
I have a large in ground pool.

At opening last year I noticed that any time the water was agitated it tended to foam and bubble. My pool guy thought that it was likely due to the algicide I used at opening and that it would slowly dissipate over the course of the spring. Unfortunately, it persisted throughout the year, though otherwise the water was perfect all year. This year at opening the water was so clear that I did not use an algicide. Once again the water foams and bubbles with any agitation. Otherwise the water has been perfectly clear, and pH, alkalinity, and free and total chlorine have been perfectly maintained. This year the pool guy thought it might be that the water was too soft, and indeed my calcium harness readings were below 100 ppm. I have added Ca gradually over the past few days and my readings are now around 300 ppm and I still have foamy water.

Any ideas?