Individuals with normal color vision will see a number, while those with a deficiency do not see it. On some plates, a person with normal color vision may see one number, while a person with a deficiency sees a different number.
Your phosphate level should be at or below 100 parts per billion (ppb). If your water chemistry and phosphate levels seem to be in check, one potential cause of the cloudiness in your pool could be dead algae. Phosphates are the food supply for algae, thus high phosphate levels promote algae growth.
Phosphates usually enter a pool in the form of Tri-Sodium Phosphate, or TSP. During shocking of the pool, or adding of enzymes, TSP is broken down into the tastiest algae food known - Ortho-Phosphate. In this free state, ortho-phosphate provides all types of algae with a good food source.