The problem may be the water has no chlorine in it and the sun has turned the pool green.
Organisms can form and can cause health problems as they multiply at a tremendous rate. Once growth starts, one algae spore can turn into ten million in approximately 10 hours.
The best way to eliminate this problem is to ensure continuous and efficient recirculation of the water through a filter. In addition to this, it’s necessary to destroy any organism that exists by chlorinating the water and adding an algaecide.
When added to the pool in sufficient quantity, chlorine will effectively kill any bacteria that may be present. However, in order for it to work effectively the pH value must be checked and adjusted.
This will clear the pool up and may then require a water polish.