Green algae is the first sign you have lost control of your water environment. There are many parameters involved in 'why', but I can help you spot what is dominant in your unique mix:

1. Exposure to sun

2. Poor water flow in parts of the pool

3. Insufficient conditioner

4. High alkalinity water

5. Substandard Chlorination process

The longer you allow algae to persist, it will really embed itself inside:

• Steps & hand-rails

• Skimmer mouths

• Robotic pool cleaners

• Returns

• The filter itself

Have your case inspected, chemistry checked and only pay for reasonable analysis & correction time.