Why pool water turns cloudy
Cloudy water is usually a loaded filter, weak circulation, or chemistry out of range. Test free chlorine, pH, and alkalinity, and read the filter pressure, before you add a clarifier. Green or yellow water is algae, not haze.
· 5 min read
A clarifier is not the first step. Green or yellow water is a different problem from a white haze.
White haze and green water
A white or gray haze still lets you see the floor, with soft edges. Green or yellow water, or a slimy wall, means the sanitizer has been low long enough for algae. Brush that loose and follow the sequence in how to balance pool water. Do not treat a green pool as a clarifier problem.
A pool that was clear yesterday and milky this morning often had a heavy swim day, a storm, or a dose that did not mix. Write down the test numbers and the filter pressure before you change anything.
Test, then read the gauge
Test free chlorine, pH, and total alkalinity. If those are off, adjust alkalinity, then pH, then sanitizer, and wait between doses. Cloudy water with a low sanitizer reading is not fixed by a clarifier.
If the gauge is about 8–10 psi over the clean baseline, the filter is holding the dirt and the water stays dull until you clean it. Cartridge, sand, and DE each have their own steps in how to clean a pool filter.
Circulation, then a clarifier
The filter only clears water that passes through it. If the pump lid is full of air or the returns are weak, fix that before you judge the water. The usual causes are in why a pool pump loses prime.
A clarifier is a later step, after the test is in range and the filter is clean. It gathers fine particles so the filter can catch them. Clarifiers are in chemicals. If the water is still dull after that, brush the floor and the waterline so the next pass has something to catch. Brushes and vacuum heads are in cleaning. Which tool does which job is in brush, vacuum, or robot.
Questions
Why is my pool cloudy when the chlorine test is fine?
The filter is often loaded, or the pump is not moving a full stream. Read the pressure gauge and look at the pump lid for air. A clarifier does not fix either one.
Should I add clarifier to a cloudy pool?
Only after free chlorine, pH, and alkalinity are in range and the filter has been cleaned. A clarifier on a dirty filter, or on a low sanitizer reading, makes the water look worse.
Is cloudy pool water the same as algae?
A white or gray haze is usually filtration or minerals. Green or yellow water, or a slimy surface, is algae. That starts with the sanitizer and with brushing, not with clarifier.