How to Get Rid of Pool Algae: A Step‑by‑Step Guide

Algae in a pool is more than just ugly. It makes your water cloudy, slippery, and unsafe for swimming. The good news is you can remove it quickly with the right tools and a proper plan.

What Is Pool Algae and Why Is It a Problem?

Pool algae is a simple plant‑like organism that grows in water when conditions are right. It feeds on sunlight, carbon dioxide, and nutrients in the water. Once it appears, it spreads quickly and can become hard to control.

There are three common types:

• Green algae: Most common and easy to treat

• Yellow or mustard algae: Clings to walls and is harder to brush off

• Black algae: Grows in cracks and is very tough to remove

Algae makes the pool look dirty and creates a slippery surface. It also clogs filters and makes sanitizers less effective.

What Causes Pool Algae to Grow?

Several factors lead to algae growth:

• Poor water circulation

• Low sanitizer levels

• Imbalanced pH or alkalinity

• Warm water and direct sunlight

• Heavy use without enough cleaning

• Debris or leaves left in the water

Algae can enter your pool from contaminated swimsuits, pool toys, rainwater, or wind.

When Should You Treat Pool Algae?

Act as soon as you see signs of algae:

• Green, yellow, or black discoloration on pool walls or floor

• Cloudy or dull water

• Slimy surfaces

• Decreased water flow or filter pressure

The earlier you treat it, the easier it is to clear.

How to Remove Pool Algae: Step‑by‑Step

Step 1: Test and Balance the Water

Use a test kit to check:

• pH (aim for 7.2 to 7.6)

• Total alkalinity (80 to 120 ppm)

• Chlorine or other sanitizer levels

Adjust if needed before shocking the pool. Algae treatments work best when water is properly balanced.

Step 2: Brush All Pool Surfaces

Scrub the walls, steps, and floor thoroughly. Use:

• A stiff brush for concrete or plaster

• A soft brush for vinyl or fiberglass

This breaks algae’s grip and exposes it to chemicals.

Step 3: Shock the Pool

Use a chlorine shock or algaecide, depending on the type of algae:

• Green algae: Standard chlorine shock

• Yellow algae: Double the shock dose or use specialty yellow algaecide

• Black algae: Triple shock and use a metal brush to scrub deeply

Always follow product directions. Run your pump and filter for 24 hours.

Step 4: Clean the Filter

Algae can clog your filter quickly. Clean it thoroughly:

• Backwash sand or DE filters

• Rinse or soak cartridge filters

Repeat filter cleaning daily during algae treatment until water clears.

Step 5: Vacuum Dead Algae

Once algae is killed, vacuum it out of the pool. Use:

• Manual vacuum to waste for green or yellow algae

• Automatic cleaners for maintenance after cleanup

Do not rely on the filter alone to remove all dead algae.

Step 6: Run the Circulation System

Keep the pump running 24 hours per day during treatment. Good circulation helps clear the water and distribute chemicals evenly.

Continue running your system until water is clean and clear.

What Products Help Treat Algae?

• Chlorine shock

• Algaecide for green, yellow, or black algae

• Clarifiers to remove fine particles

• Enzyme products to prevent regrowth

• Pool brushes and vacuums

Use these together for faster and longer‑lasting results.

Who Should Treat Pool Algae?

Most pool owners can handle mild to moderate algae outbreaks themselves. Follow label directions and be consistent.

Call a professional if:

• Black algae returns after treatment

• Water stays cloudy for more than 3 days

• You notice equipment problems or leaks

Experts can inspect your system, check for hidden issues, and do a deep clean.

How to Prevent Algae from Coming Back

1. Maintain chlorine or sanitizer levels

2. Brush walls and floor weekly

3. Run your pump 8 to 12 hours a day

4. Shock weekly during peak season

5. Remove debris daily

6. Keep water balanced and test often

7. Clean filters regularly

By following these habits, you can keep algae away and enjoy a sparkling pool all season long.