This can be caused from a number of problems. Here are some possibilities:

- pH Too Low or Too High
- Improper Water Balance
- Combined Chlorine
- Excessive Organic Waste
- High Total Dissolved Solids
- Algaecides
- Algae
- High Chlorine (above 10 PPM)

TREATMENT

1.) Test all water factors.  Balance water.  See Water Balance/Saturation Index.  If water tests Perfect and looks Perfect, shock pool to 10 PPM free chlorine to remove any traces of organic waste.

2.) Spas should be drained periodically due to build up of chemical additions and organic matter.