How to Remove Algae In a Pool

If you have green pool water, it could be from algae.

Algae is a common problem in swimming pools and can appear suddenly. It clogs filters, leads to poor water circulation and inhibits the effectiveness of pool chemicals.

It's also unhealthy. Swimming pools with algae are a breeding ground for harmful bacteria. Black algae, or blue-green algae, is a dangerous cyanobacteria.

Neither chlorine nor the pool filter will clear it on their own, so how do you get rid of this nuisance?

What Causes Pool Algae Growth?

Rain and wind, or pool equipment contaminated from natural bodies of water carry spores into the pool, where it spreads and grows. Sunny conditions, low chlorine levels, improper pH levels, dirty filters, or pool circulation all allow it to flourish.

How Can I Prevent Algae?

Prevention is easier than removal and treatment.

A pool cover is an excellent way to prevent algae. Also, always clean your filter system and wash off potentially contaminated swimwear or equipment.

Keep your pool water chemistry balanced, testing pool chemicals regularly. Keep phosphate levels low, as algae feed on it. You can use a phosphate remover if necessary.

Algaecide, in small, weekly doses, prevents it from growing. A weekly pool shock treatment, or super-chlorination, can help, too.

Types Of Algae

The type of algae impacts the treatment.

Green Algae

Green pool algae are the most common and spread quickly, but it's also the easiest to kill. It's usually caused by poor sanitizing and filtering, and a high pH. It causes green, cloudy pool water. The green slime will float or grow on pool walls. Its colour varies from teal green to dark black green, at its worst. Thorough vacuuming, brushing, shocking and filtering can remove it.

Mustard or Yellow Algae

Yellow pool algae are less common but harder to remove. It appears as a yellowish-green sand or pollen sticking to pool sides in shadier spots. It's chlorine-resistant and may need several rounds of brushing pool surfaces, adding higher shock doses to your pool water and possibly a specific algaecide.

Black Algae

Black algae look like black spots on your swimming pool wall. It's very difficult to remove because the part that you can see has a protective layer and it has strong, deep roots that grow into walls. It'll take several rounds of thorough cleaning, and even higher levels of shocking.

Pink Algae

Pink algae, or pink slime as it is sometimes called, is an airborne bacteria that require a pink algaecide to remove it from your pool.

Removing Algae From Your Swimming Pool Water

There are several steps to get rid of algae. Attention to detail is critical; any remaining spores spread and grow quickly.

Vacuum Manually

Automatic pool cleaners aren’t thorough enough. Vacuum using the waste setting to bypass your filter, so contaminated water doesn't recirculate back into your pool.

Brush and Scrub

Brush the entire pool vigorously to remove as many algae as possible. This cuts down the time to kill algae. Scrubbing the algae off helps chlorine reach all the algae better and loosens up contaminants for removal. Cloudy water will make it harder to see down to the pool floor.

Pool Chemistry

Test alkalinity and pH levels. A higher pH is common during an algae bloom. Adjust levels as needed; this allows shocking to work better. Retest when necessary.

Shocking

Super-chlorination, or shocking, is the best way to treat algae, as the extra free chlorine kills it. Calcium hypochlorite or Sodium Hypochlorite shock is effective.

Usually, green algae need a double dose; mustard algae, a triple dose; and black, a quadruple dose. Shock at night for the best results and run your filter overnight to circulate.

You may need to repeat the brushing and shocking process.

For mustard algae growth, a yellow algaecide is specifically needed, while a black algaecide is used for a black algae problem.

Vacuum Again for Dead Algae Debris

Use a pool vacuum or backwash the pool to remove dead algae. If necessary, repeat the whole process after two to four days.

Filtering

When a pool shock has done its job, the algae turns grey as it dies, settling on the bottom and turning the water a cloudy blue colour.

A sand filter usually can't remove the dead algae particles, so vacuum them out using the waste setting. If you have a cartridge filter, you'll need to clean the filters thoroughly afterwards.

Run the filtration system continuously for at least eight hours or until the water clears.

Test Again

Ensure your chemical levels are balanced, chlorine levels are normal, and cyanuric acid and calcium hardness levels are good.

Clean Your Filter

To avoid a contaminated filter reintroducing algae spores back into your pool, replace or thoroughly clean your filter cartridges.

What About a Saltwater Pool?

Getting rid of algae in a saltwater pool is the same process as a regular chlorine pool.

Worry-Free Maintenance

What if you didn't have to worry about any of this, and could just come home and swim whenever you wanted to?

For hassle-free swimming pool maintenance in Toronto, contact People for Pools at 647-710-8926, 1585 Britannia Rd E, Unit B3 Mississauga, ON L4W 2M4, and enjoy a worry-free pool experience without harsh chemicals.