Pool filtration not working: what to do so the water doesn’t turn green

Short answer: When filtration stops, limit swimming, remove debris by hand, keep an eye on disinfection, and restore circulation as quickly as possible.

Without filtration, even well-treated water deteriorates quickly. The problem is worst in heat, after a storm, or under heavy bathing load.

How to identify the cause

• The pump isn’t running or is humming.
• No flow at the jets.
• The water level in the skimmer isn’t moving.
• Filter pressure is zero or outside the normal range.

What to do now

1. Turn off the equipment if it sounds unusual or is running dry.
2. Check the baskets, skimmer and water level.
3. Remove debris with a net.
4. Test pH and disinfectant level.
5. After the repair, filter for longer and re-test the water.

When it’s better not to swim

• When the water has been standing for several days without checks.
• When it’s cloudy or green.
• When the disinfectant level is unknown.

Prevention

• Clean the baskets regularly.
• Don’t let the pump run dry.
• Check pressure and flow.
• Have a plan for power outages.

When to call a service technician

Call a service technician if the motor hums, there’s a leak, air is being drawn in, or the breaker keeps tripping.

FAQ

How long can a pool go without filtration?

Longer in cold, clean water; only briefly in heat and with swimmers using it. Without testing, it’s safe to assume the water will deteriorate quickly.

Should I add more chlorine?

Only based on a test. Without circulation the chemistry won’t mix properly, so it won’t fix the filtration problem.

Sources

• CDC – water testing in home pools and hot tubs
• CDC – hot tub safety
• Modrá střecha – pool discussion forum (Czech)
• Reddit r/hottub – common questions from hot tub owners
• Trouble Free Pool – community pool water advice
• ALBIXON – most common pool water problems
• ARIVA – green pool water
• Upravvodu.cz – pool water problems
• Laboratoř Monitoring – hot tub water treatment

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