How to Get Rid of Black Algae in Pool

Black algae are one of those pool issues that every pool owner dreads, given how hectic they can be to remove. However, the good news is that it is still reasonably easy to eliminate from the pool if you know what to do.

When dealing with black algae, you need to understand what it is and why it grows in your pool, and the best way to remove it. Also, it is always better to know how to prevent it before it forms, as this will save you money and the hassle of dealing with the problem.

What is Black Algae?

Despite what its name suggests, black algae are actually bacteria (cyanobacteria, to be more precise). Also, they are naturally blue-green as they also contain chlorophyll like most other algae types.

The black color comes from the fact that besides chlorophyll, black algae also contain other water-soluble pigments that will combine with its blue-green color to make the bacteria look black.

Black algae can lead to the formation of cyanotoxins like most other cyanobacteria, and it also creates a suitable habitat for E. coli and other harmful bacteria. Therefore, it can pose a significant health risk to swimmers and pets, which is even more so if they swallow the pool water.

How to Get Rid of Black Algae in My Pool Fast

What You Will Need

• Filter cleaner
• Algae brush
• Algaecide
• Pool shock

Step by Step Directions

Step 1: Sanitize Everything You Will Use

You do not want to add more algae to your pool as you attempt to deal with your black algae problem. Therefore, before anything else, you need to sanitize everything that you will use for the job.

The best way to do this is by washing and scrubbing things like pool brush and your safety gloves with a chlorine solution and rinsing with a lot of clean water.

Step 2: Clean the Filters

Once the tools are clean and sanitized, the next step is to clean your filters. Before you even start scrubbing the algae from the pool wall and floor, you need your filters to be clean so that they can trap the contaminants you scrub off.

Even if you do not see any algae in your filter, the fact that you have some in the pool makes it inevitable that there will be lots of it in the filter. Most manufacturers provide clear directions for cleaning their filters, so this should not be a problem.

Also, note that if you use the sand or DE filters, you will need to do some backwashing and lots of rinsing after cleaning to restore them to good working condition. Backwashing prevents sand from getting to the pool water and ensures it sits nicely in the filter for maximum effectiveness.

Step 3: Test and Balance Pool Chemistry        

Next, you need to test your pool chemistry and ensure everything is at the optimal level. Here you have to test critical parameters like chlorine, pH, and alkalinity and ensure you balance them to have the required levels.

Chlorine levels should be between 1 and 3 ppm, pH 7.2 to 8.0, and alkalinity should be 80 to 120 ppm. A digital pool test kit like the AquaChek NP207 Trutest Digital Reader will be handy here as it provides more accurate readings.

Step 4: Brush and Scrub the Pool Thoroughly

With pool chemistry perfectly balanced, you can now get to the hard work, which entails thoroughly scrubbing your pool’s surfaces. Before this, you can also add algaecide to the water to kill the algae and make it easier to scrub off.

Besides ensuring you do a thorough scrub, you also have to use a pool brush that will not damage your finish but is still effective at removing the algae.

For example, only use a brush with stainless steel bristles on hard finishes like gunite or plaster. Soft nylon bristles are the best for delicate vinyl finishes and liners.  However, you still have to be quite aggressive since black algae can be very stubborn.

Step 5: Shock the Pool

It would help if you allowed the pool’s filtration system to run for a while to remove the loose black algae before shocking the pool.

Shocking will help kill any algae that your filtration system does not remove, and it is also handy for restoring the pool to good overall conditions. Given how stubborn black algae can be, you should use much more shock than you would for your routine pool cleaning.

Step 6: Clean the Filter Again and Run the Pump

After giving the shock the required amount of time to work, you should clean the filters again to ensure no residue of the black algae lingering there. Once the filters are clean, you need to rerun the pump to circulate the water for further filtration and cleaning.

Step 7: Test and Balance Pool Chemistry Again

The last step is to test the pool chemistry again. Here you want to check whether the steps above have knocked things like pH, alkalinity, and chlorine levels off balance.

After the tests, you should balance anything that requires balancing, and the pool should now be free of black algae and ready for use.

How to Prevent Black Algae in My Pool

1. Always keep pool chemistry in perfect balance, meaning the pH, alkalinity, chlorine, and calcium hardness levels should always be optimal.

2. Maintain a weekly pool shock routine and make sure you shock it after periods of heavy usage or severe weather.

3. Make sure you sanitize all your pool equipment and other accessories and fixtures that interact with your water, such as pool toys, slides, and ladders.

4. Remember to run the pump long enough every day, depending on the pump type, your pool size, and turnover rate.

5. Make it mandatory for all pool users to rinse their bodies thoroughly before jumping into the pool. You can make this easier by installing a showerhead near the pool.

Bottom Line

Black algae can be quite troublesome, and it will often take a lot of effort and dedication to deal with the problem. However, things should be easier if you follow the steps above.

That said, it is always better to prevent it from invading your pool by following the tips above to keep your pool water clean and sanitary, as this will save you both time and money.