Green Algae Problems in Saltwater Swimming Pools

What causes it? How to fix it permanently? (Easy Guide for Pool Maintenance)

Many saltwater pool owners frequently encounter Green Water / Algae blooms, even when the salt chlorinator is running constantly.
In reality, a Salt Pool is simply a type of Chlorine Pool. If the water balance is not appropriate, algae can grow just as easily.

Major Causes of Green Algae in Saltwater Pools

1) Insufficient Chlorine

• The salt chlorinator is not running for enough hours.
• The Output percentage is set too low.
• High bather load / Rain / Strong sunlight causes chlorine to deplete quickly.

Note: When chlorine drops below 1 ppm, algae will start to grow immediately.

2) pH Level is Too High

If the pH > 7.8, chlorine cannot function effectively, even if the ppm reading seems sufficient.
The result is: "Chlorine is present, but it cannot kill bacteria or algae."

3) Poor Water Circulation

• The pump is running for too few hours.
• Inlet nozzles are not distributing water throughout the entire pool.
• There are "Dead Spots" (e.g., behind ladders or pool corners).

These stagnant areas are where algae starts to grow first.

4) Dirty Filter / Not Backwashing

If the sand filter or filtration media is clogged:
= It cannot trap dirt effectively.
= It becomes a "Food Source" for algae.

5) Dust, Leaves, and Organic Debris

Homes with trees near the pool often face this issue. Organic matter accelerates algae growth, especially during the rainy season and sunny days.