Clear and clean pool water is not enough with the balance of chemicals. One of the more frustrating problems for a pool owner is black algae in pool. Most often, green algae grows across the pool’s surface, but not black algae. This can firmly attach to the walls, floors, and other surfaces within the pool, making it much more difficult to remove.
Knowing the source of black algae, recognizing it, and cleaning techniques will keep the pool in a healthy state while reducing the recurrence of algae problems.
What Is Black Algae in Pool?
Black algae in pool is actually a type of cyanobacteria which forms black spots or patches on the surface of your pool. Even though it is commonly referred to as algae, it is actually quite different from the typical green algae because it forms very hard protective layers which enable it to survive even the harshest conditions in your pool.
Black algae usually appears as:
- Small black or blue-green spots
- Dark patches on pool walls and floors
- Rough areas that are difficult to brush away
It usually grows in spots with poor circulation, cracks, or textured surfaces, and in areas where pool maintenance is inconsistent.
What Causes Black Algae in a Pool?
Black algae usually develops when organic growth is allowed to spread within the pool environment. Several factors can contribute to the problem.
Poor Water Circulation
Low water movement in certain areas can create ideal conditions for the growth of algae. If certain parts of the pool are not getting enough filtered and sanitized water, then algae can attach and develop.
Improper Chlorine Levels
Low or inconsistent levels of chlorine would make it easy for algae to grow. Chlorine is one of the primary elements that helps control microorganisms in the water of a pool. Proper sanitizer levels must be maintained as an integral part of preventing algae.
Poor Pool Maintenance
Irregular brushing, cleaning, and water testing provide enough opportunity for algae spores to take hold of the pool’s surface.
Contaminated Equipment
Sometimes pool accessories, brushes, floats, and cleaning tools bring back algae spores into the pool if they are not cleaned properly.
How to Identify Black Algae in Pool
Black algae may be mistaken for dirt or stains, but here are some clues to help you identify it.
A black algae spot usually:
- Appears as small dark dots or clusters
- Feels raised or rough compared with the surrounding surface
- Stays attached when lightly brushed
- Returns quickly after normal cleaning
Unlike dirt, it has roots that can penetrate porous pool surfaces, which is why simple brushing does not often remove it.
How to Get Rid of Black Algae in Pool?
Physical cleaning and water treatment should be done simultaneously to ensure complete removal of black algae in pool.
Step 1: Test and Balance Pool Water
Check your pool chemistry first since, before treatment, it must be chlorine, pH, alkalinity, and sanitizer levels within the recommended range.
Balanced water will allow the cleaning products to work better.
Step 2: Brush the Affected Areas
Use a stiff pool brush to scrub the spots of black algae aggressively. Brushing is vital because it breaks the outer protective layer and allows chlorine or algae treatment to get deeper.
Pay special attention to:
- Pool walls
- Corners
- Steps
- Grout lines
- Textured surfaces
Step 3: Use Algae Treatment
A pool algaecide or shock treatment designed for algae control can help eliminate remaining growth.
For severe black algae problems, repeated treatment may be necessary because the algae can be deeply attached to surfaces.
Step 4: Keep the Filter Running
After the treatment, run the pool filtration system all the time, to help remove dead algae and keep water circulating.
You may also need to clean or backwash your pool filter depending on the type of filter and the condition of the water.
Can a Pool Filter Remove Black Algae?
A pool filter helps remove suspended particles and dead algae from the water, but it cannot usually remove black algae which is attached to the pool surfaces by itself.
Different filters work in different ways:
- Cartridge filters capture debris and particles from circulating water
- Sand filters remove larger suspended contaminants
- DE filters provide finer filtration for smaller particles
However, physical removal through brushing is still required since black algae attaches directly to the pool surfaces.
How to Prevent Black Algae in Pool
Preventing black algae is easier than removing it. The risk of algae can be cut significantly with regular pool maintenance.
Maintain Proper Water Chemistry
Test your pool water regularly and keep it at a balanced chlorine and pH level.
Brush the Pool Regularly
Even if the areas look clean, it is recommended to brush them from time to time so that algae doesn’t get a chance to attach.
Improve Water Circulation
Check if the pumps, filters, and return jets are in good working condition. Proper circulation will help in the even distribution of sanitizer.
Clean Pool Equipment
Wash brushes, nets, and accessories to avoid reintroducing algae spores into the pool.
Keep the Pool Filter Clean
A dirty or clogged filter reduces water circulation as well as the performance of filtration. Regular cleaning of the filters helps in maintaining better quality of water.
Conclusion
Black algae in pool water can be removed, but it is difficult since it is strongly attached to pool surfaces and grows deeper than ordinary algae. The best solution is a combination of proper water balance, strong brushing, effective filtration, and consistent maintenance.
By keeping your pool clean and maintaining your filtration system regularly, you can reduce the chance of black algae returning and enjoy clearer, healthier pool water throughout the swimming season.