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All about Swimming Pool Algae

By December 7, 2022May 12th, 2023Maintenance

Your swimming pool is your safe area. You want to dive in, swim, and relax with your family and friends and create memories to cherish.

If, however, the swimming pool water looks cloudy, greenish, and slimy, you would rightly worry about diving in. All homeowners like crystal clear water in their swimming pool but when algae invades the water, your pool will look like a health hazard instead.

As with everything in life, prevention is the best way to protect your swimming pool from algae. Thankfully, even if algae have already invaded the pool water despite your best efforts, there are always ways to combat algae growth.

What Are Algae?

Algae are photosynthetic organisms that thrive in humid and warm conditions. They feed on light and nutrients often found in dirt, debris, and dust.

Algae spores are everywhere around us, including inside your swimming pool. When the pool water is properly balanced and circulated, algae can’t grow. When, however, conditions favor algae development, your swimming pool water takes the characteristic algae-like green look.  

What Types of Algae Are There?

There are four major types of algae: green, yellow, black, and pink.

Green Algae

This is the most common type of algae and the easiest to combat. It looks like thin slices of green slime floating on the water. It is usually found in swimming pool areas where the water is not filtered properly. Undisturbed water is the perfect setting for algae to thrive.

Yellow Algae

Yellow algae are often mistaken for pollen dust, because of the common color both conditions display.

It is harder to deal with than green algae because the yellow algae spores like to hide in shady areas of the pool such as behind the pool steps, in dark corners, and behind lights.

Black Algae

Black algae are the most difficult type of algae to get rid of, as they display features of mold. Black algae are bacteria with roots that cling to surfaces such as tiles and concrete. To eliminate black algae, you need to scrub them off surfaces to break the external membrane and detach them from their roots.

Pink Algae

Pink algae are relatively rare but have similar characteristics to black algae. They are slimy and have a reddish-pink color, hence the name. Pink algae are made of bacteria and create a floating layer over the swimming pool water.

What Causes Algae Growth in Swimming Pools?

Because algae spores are all around us, it is not difficult for the spores to find the right conditions to thrive in swimming pools.

Out-of-Balance Water Chemistry

Swimming pool water must be properly balanced. Alkalinity, pH, and other chemicals must be in perfect sync. When the pH is too high, the water becomes the perfect breeding ground for algae.

Also, low chlorine levels help algae thrive. Chlorine kills algae and bacteria and when the swimming pool doesn’t have enough chlorine, algae spores can grow.

Poor Water Circulation

Swimming pool filters should run for at least 8 to 12 hours per day. If the water doesn’t circulate consistently, swimming pool areas will have undisturbed water where algae will find refuge.

Sometimes the swimming pool filter is not adequate for the size of the swimming pool and the quantity of water that needs to be filtered. In these cases, you either have to run your filter for longer or switch to a more suitable filter for your pool.

Contamination from Other Water Sources

Sometimes, a random event can cause algae to grow in the swimming pool. For example, if a person wears a swimsuit in the ocean and dives in the swimming pool without rinsing the swimwear, they could transfer algae spores to the water.

Debris and Dust Amassing in the Swimming Pool

A swimming pool that hasn’t been used in a long time or a pool that has amassed quantities of debris and dust—as, for instance, after a rainstorm—offers the perfect environment for algae to settle in and grow.

What Are the Effects of Algae on Swimming Pool Water?

Poor Water Quality

Swimming pool water that is contaminated with algae looks positively unappetizing. It’s cloudy and murky and has a slime-like look to it. Nobody likes to swim in such water conditions.

Algae Clogs Pump Filters

As algae pile up, they clog the pump filters and make them less effective. Your pump can’t clean the pool efficiently. A dirty pool is a perfect environment for algae colonization.

Chlorine Can’t Fight Other Contaminants

In the presence of algae, chlorine is so busy fighting off algae that it can’t exterminate other dangers such as E-coli and other harmful bacteria. People shouldn’t swim in the swimming pool because they risk getting sick from these.

Risk to Human Health

While not all that dangerous to human health, algae can still cause skin sensitivity and rashes. Also, because of poor chlorine activity, swimmers can get sick from the other bacteria floating around.

How Do You Fight Algae Growth?

The two main ways to get rid of pool algae are to clean your pool’s surfaces manually and chemically shock the pool water to exterminate the algae.

Scrub Pool Surfaces

Many homeowners choose to run their automatic pool vacuum to rub the surfaces but cleaning the interior of your pool manually will deliver better results. You want to get rid of even the smallest remains of algae residue because you don’t want to have a similar problem a few weeks later.

You should scrub the pool’s walls and floor and reach into the tiniest corners where algae are hiding. Remember that the water will get murky when you start cleaning, as algae will start floating on the surface. For better visibility, start with the areas that are more difficult to reach and continue with the easier ones.

Shock Your Pool

The aim of the scrubbing exercise is to loosen all the algae that are attached to surfaces. Once this is done, you can shock your pool with calcium hypochlorite to kill the algae microorganisms. Because chlorine is sun-sensitive, choose to shock your pool at dusk or at night so that chlorine can have its full effect away from the sunlight.

Run the filter for 12 hours for the shock to fully circulate in the pool and reach all pool areas. You want your whole swimming pool to be fully sanitized from algae. The swimming pool will turn cloudy because dead algae will be floating on the surface.

You then have to run the filter again to clear away the shock and all algae residue and restore the water balance.

Test the Water

Test the water for pH levels, alkalinity, and other chemicals to make sure everything is balanced and you don’t risk another algae overpopulation.

Clean Your Filter

Algae-contaminated water has entered the swimming pool’s filter. Once you know your swimming pool is algae-free, clean the filter with muriatic acid to exterminate all remnants of algae. Otherwise, the water will filter through the pump and return to the pool with algae particles the next time you run your pump.

All equipment used during the scrubbing and cleaning phase should be sanitized so you don’t transfer algae back into the water.

Repeat if the Algae Problem Is Extensive

If the algae problem persists or you see spots of algae activity in tiny spots, nooks, and crannies, you may have to repeat the whole scrubbing and shocking exercise to ensure it is completely algae-free.

How to Prevent Algae Development

Be Consistent with Pool Maintenance

Swimming pool maintenance is paramount. To avoid algae development, you need to test the swimming pool water weekly and make sure that chlorine, alkalinity, and other chemicals are perfectly balanced. Remember that algae spores are present all around and will readily multiply in favorable conditions.

Run the Filter

As long as pool water is constantly moving, it is very difficult for algae to grow. Run your pool filter for at least 10 to 12 hours per day, especially after heavy use or rain.

Cover Your Pool If You Are Not Using It

If you won’t be using your swimming pool for some time, you should cover it to prevent dirt and debris from landing on the water.

Use an Algaecide as a Preventative Measure

There are algaecides in the market that you can use as a preventative measure against algae. Consult Waterside Poolscapes about swimming pool products.

Clean the Pool Filter and Skimmer Regularly

The pool filter is the place where all debris and dust land after cleaning the water. Clean the filter regularly to stop algae from multiplying.

Act Fast If You Spot Algae

Don’t let algae spores multiply! It is far easier to get rid of a small algae colony compared to a large one. When you spot suspicious algae growth, use algaecide or shock your pool right away to exterminate the organisms.

How Long Does It Take to Get Rid of Swimming Pool Algae?

Once you have scrubbed the pool surfaces and shocked the water, you should start seeing improvement within 24 hours. You then need to re-balance the water chemicals and test that everything is in order before you can swim in your pool.

Contact Waterside Poolscapes for Your Algae Problem

If scrubbing, cleaning, shocking, and testing your swimming pool water sounds like an ordeal, you only need to call Waterside Poolscapes at 281-690-4810 and our experienced crews will take care of your algae problem for you.

We have the right know-how, extended experience, and appropriate chemicals to eliminate algae colonies in pools and return the water chemistry to a safe balance.