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.
Phosphorus is one of the basic building blocks of living matter. It is present in every living creature, and in the water of every reef tank. Unfortunately, it is present in excess in many reef tanks, and that excess has the potential to cause two big problems for reef keepers. The first is that is can drive excessive growth of undesirable algae. The second is that it can directly inhibit calcification by corals and coralline algae.