Phosphates in pool water are measured on a different scale than all other elements. Importantly, phosphates are measured in parts per billion (PBB), not part per million (PPM). Remember, that this is because if they were measured in PPM then the numbers would always appear to be very low. For example, 5PPM of chlorine can also be correctly expressed as 5,000PPB. Notice how dramatic 5,000PPM sounds compared to 5 PPM.
A different perspective on phosphates in water and how they are sometimes a little overplayed in the pool industry can be found here.
Pool always turning green?
If your pool water seems to always be on the verge of going green or cloudy, then high phosphates in pool water is often the cause. Also, if the free chlorine is not high enough this can make clear water harder to achieve. We have a page about this that provides further information about this.
If your water is turning green and there are no phosphates then it could be time to shock chlorinate the pool water. This will kill off the chloromines and allow your chlorine to be more effective in killing algae. It is a good idea to shock chlorinate your pool every 6 months.
In summary, it is important to remember that there are many aspects of water chemistry. Therefore, maintaining a broader perspective is important. Sadly, not all pool shop staff are trained to see beyond what the computer tells them to sell. Therefore, this means some poor folks end up on a endless product merry-go-round that never seems to solve the problem.