What Causes Black Algae In Pool
Black algae or blue-green algae in pools is usually transferred from natural bodies of water like oceans, ponds, and lakes by clinging onto swimwear. If the swimwear is hasnt been washed before using a swimming pool, the algae can be transferred into the pool.
Black algae doesnt naturally occur in backyard swimming pools. Unwashed swimwear is the primary way it is transferred.
Once inside the pool, it can multiply quickly.
A Few Things That Work
We have found Black Algae in some pretty interesting places. Here, Ashley takes us through several different methods that work on eliminating it.
2018 was a pretty exciting year for us as we dove deeper into swimming pool black algae. Not only did we confirm that black algae was actually cyanobacteria, we were able to break it down even further identifying the constituents of the colonies by genus.
In doing this, we had found that we were the first known folks to research swimming pool black algae in over thirty-five years. The last known research document Laboratory Comparison of the Effectiveness of Several Algicides on Isolated Swimming Pool Algae written by R. P. ADAMSON AND M. R. SOMMERFELD of the Department of Botany and Microbiology, Arizona State University, Tempe, Arizona 85281 appeared in the APPLIED AND ENVIRONMENTAL MICROBIOLOGY, in February of 1980. I hadnt even made it into High School yet when this publication came out ? and Im old!!! Interesting to see ? that no one else has really even looked at this stuff since I was thirteen.
So, next we decided to see if we could investigate some methods in How to Rid a Swimming Pool of black algae. We were actually able to locate a 230,000 gallon test pool with over fourteen years of black algae growth for this experiment.
What Causes Algae To Form In A Pool
The main cause of algae in a swimming pool is low free chlorine level. Algae is rampant in hot and humid climates or during the summer, simply because chlorine reduces faster as water temperature increases leaving your pool vulnerable to algae and bacteria.
As such, the only way to keep algae and bacteria away is to maintain recommended FC level of 3ppm all the time by adding chlorine whenever it drops below 3ppm and this should be done on a daily basis. But don’t think, even for a moment, that maintaining chlorine levels is enough: You need to maintain an appropriate balance of all chemicals in your pool because they affect how long chlorine lasts in your water.
Most chemicals used in the pool, such as pH chemicals, sanitizers, alkali, calcium, stabilizers, and more, will affect how chlorine works and how it is consumed. For this reason, the only perfect way to avoid algae or cloudy water is to constantly maintain the correct chemical balance in your water, which means using an accurate pool water testing kit.
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What Is Black Algae
True algae is an aquatic plant belonging to a group that includes everything from single-celled organisms to seaweed. This is why when you think of algae, you think of it as being something greenit usually is.
Like most plants, green algae contains chlorophyll, the pigment that gives it its green color. Chlorophyll is also the substance that allows a plant to perform , the process by which the plant uses light to synthesize food from carbon dioxide and water.
So if black algae is cyanobacteria, which is blue-green in color, why is it black?
Cyanobacteria contains chlorophyll, which contributes to its blue-green color. But it can also contain other water-soluble pigments that, when combined with the blue-green pigment, make the bacteria appear black.
Unbalanced Pool Ph And Not Enough Sanitizer
An unbalanced pool pH and lack of sanitizer will make it possible for black algae to multiply in the pool.
When the pool pH and water chemistry is unbalanced, the effectiveness of pool chemicals like chlorine will be reduced. This will allow black algae bloom. pH should be between 7.4 and 7.6.
And for pools to kill off all bacteria, its essential the correct level of chlorine is maintained 1-5 ppm with 3-5 ppm being ideal. If you have a saltwater pool, its possible the chlorinator isnt working correctly. Check out: 13 Reasons Why Saltwater Chlorinator IS Not Working or Generating Chlorine
So now you know the cases of growth and spread of black algae in pools. Now how do you get rid of black algae?
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Is Black Algae Dangerous Or Harmful To Humans
Yes, Black Algae can cause a person to get sick and cause illness. The black or bluish-green spots will be a deterrent to any swimmer.
Swimming in water infected with black algae can be enough to cause illness. The probability and severity of illness are increased if you accidentally swallow the infected water.
You could experience anything from Stomach Cramps to Nausea and possibly Vomiting. Be careful of your pets too. Make sure they do not drink this water either as they will also get sick.
This is what I have been able to do to treat black algae and stop it from returning and the pool chemicals that I have used.
What To Do About The Black Algae In Your Pool
If you look closely in your bathroom, you might notice a black growth between the tiles or around your bathtub, underneath or around the silicone seams.
That is more or less similar to the black algae that, if youre not paying close attention, may infest your swimming pool as well. Since it is quite impossible to prevent algae from being transported around by wind, rain or people carrying things from outside areas into the swimming pool, the only thing you can do is do proper pool maintenance to prevent these algae, especially the black kind, from taking root.
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Pool Algae Control & Prevention
Pool algae occurs for many reasons. Low or inconsistent chlorine levels, faulty pool filtration and poor water circulation may be to blame. Preventing pool algae from flourishing helps to keep your pool operational so you can enjoy it all season long.
- The key to an algae-free pool is regular maintenance. Here are some tips to help you prevent algae from flourishing again.
- Test and balance your pool water weekly. The ideal pH range for swimming pools is 7.2 – 7.6.
- Check your filtration system weekly to ensure its working to properly circulate the water.
- Brush the pool surfaces weekly to remove algae that may be building up.
- Shock your pool water weekly to remove contaminants and clear up cloudy water.
- Add a preventative dose of an algaecide to your pool every week after shocking. Algaecides not only kill algaethey can prevent its growth as well.
- Clean all toys and swimwear that have been in natural bodies of water before allowing them into the pool to prevent the transfer of algae.
Now that you know how to get rid of algae in the pool, you’ll be able to help prevent it with easeand treat it when necessary. The sooner you tackle the algae problem, the easier it is to get rid of green algae, black algae and mustard algae. The Home Depot delivers online orders when and where you need them. Shop pool chemicals, accessories and algaecides, and have them delivered as soon as the same day.
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Vacuum The Pool Floor
First, you should completely vacuum the coarse dirt from the pool floor with a pool vacuum.
The dirt and the fine suspended matter impair scrubbing with the steel brush and would only be whirled up.
In the worst case, when you brush, you will miss some places where the black algae are sticking.
To prevent this from happening and keep the view clear, I may recommend a battery-powered pool vacuum.
You can skip this step if there is no heavy soiling from leaves or sand in the pool.
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How To Add Liquid Chlorine To Kill And Get Rid Of Algae
Depending the level of your Cyanuric acid in your water, raise your FC to shock level. The recommended Cyanuric acid level to avoid using much of chlorine is always 30ppm, which requires 12ppm FC shock level and FC should not go below 6ppm which is the maximum range.
Very important whichever shock level and Cyanuric acid level you choose to work with, test your FC after every hour and raise it back to the shock level when it reaches the maximum FC range, which is simply the level your FC should not go below in order to be able to kill all algae.
Cya of 40ppm will need 16ppm FC and shouldn’t go below 7ppm, Cya of 50ppm will need 20ppm FC and should not go below 8ppm, and Cya of 60ppm will need 24ppm FC and shouldn’t go below 9ppm until your water is free of algae.
Spare enough time to kill and get rid of algae because the process of testing FC and raising it back to the shock level might take a couple of days, and sometimes it may go up to a week or so depending on the algae you are fighting and how strong it has established itself in your pool.
Very high FC levels is very destructive to pool parts and if your Cyanuric acid is higher than 30ppm, you will have to lower it first by draining and refilling 1/4 to 1/2 of your pool water.
Finally, when your FC get down to 3ppm, balance all your pool chemicals starting with the pH, Cyanuric acid, TA, and CH.
Conditions For Black Algae Development
Algae prefer dirty water, and your pool water can provide the perfect conditions if it is not filtered. That can happen even when you maintain balanced water chemistry.
The algae can emerge if the skimmer or filter is clogged, meaning that the water is not circulating freely. It can also grow if you do not run the filtration system daily, or the motor is damaged.
The water can become cloudy if the system is not working correctly, and that means the conditions are perfect for black algae growth. Once you notice black spots on the walls, floor, or surface, know that the alga has established itself.
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Handle Your Swim Suit Appropriately
You need to be very careful with your swimming suit if you want to prevent the occurrence of black algae.
After swimming in the ocean, you must clean and dry your swimsuit to prevent any last-hour misadventure.
For all those who dont know that the black algae can get into your pool in numerous ways, it is really important to understand that one of the most common ways of algae blossom is the use of a swimsuit that has been previously used in ocean water.
The algae spore present in the ocean water would stick to the swimsuit and hop off in the pool for the very first chance it will get there.
So, be sure to bleach the swimsuit before using it in your pool.
Clean The Pool With A Steel Brush
Chemical agents are not enough because black algae are difficult to remove without a suitable brush due to the slime layer and its complex shell.
Scrub the pool thoroughly, and a second time with the steel brush if necessary.
Small black spots on the floor or the walls can be removed with a targeted application of chlorine granulate.
This is how it works: Break a chlorine tablet and rub the black algae with the edge.
Wear gloves or use a holder for the tablet.
As soon as the algae turn brown, they have died and can be brushed off.
Tip: Do not use a steel brush in a liner or pvc pool. In this case, you use a normal pool brush and scrub longer.
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How To Tell If My Pool Has Black Algae
As mentioned above, black algae actually have more similarities to mould in terms of appearance. Given the work that needs to be done removing black algae, you want to make sure youre looking at the right thing!
Beyond its colour, here are some other tell-tale signs to watch out for:
- – The location black algae usually form on rough surfaces, such as plaster or cracks.
- – It will often appear as small dots or clumps.
- – Black mould can be seen floating in the water, although it will be dead in this state.
- – Unlike pool stains, black mould can be scraped off, although it is challenging.
What Causes Algae In A Pool
Algae grow where the water circulation is low. Hot and warm weather, as well as different residues in the water, can help the development of algae.
Therefore, algae growth mainly occurs in spring and summer. The most common types of algae in pools are green algae.
Brown algae show up as coats on the pool floor and on the side of the walls.
Yellow algae occur less often and develop a dusty residue on the ground. Bacteria arise as a result of a lack of cleaning routine on the walls or on the floor.
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Brush The Pool Walls And Floor
If your pool surface is gunite or concrete. Then I suggest using a very stiff-bristled brush or a stainless steeled bristled brush.
If your pool surface is fiberglass or vinal. Then I suggest using a soft-bristled pool brush.
Now that you have chosen a suitable brush for your pool surface, its time to get brushing. Now you need to brush the black algae from the sides then the bottom of the pool.
What this does is loosen the black algae from the pool wall and floor surfaces and puts it into the water.
This is where the pool shock will take over and kill the black algae.
Remember the black algae is very stubborn and grows into the cracks and tiny crevices of the pools plaster. Thats why, if after the first round of brushing you still see some black algae spots left. Brush for the second time.
If after the second round of brushing there is still black algae spots then its time to use the chlorine tablet.
Put on your chemical-resistant gloves and eye goggles. Break a 3-inch chlorine tablet in half and fit it into a Pentair Algee-Gon 3 Inch Chlorine Tablet Holder with the broken tablet edge facing outwards. Attach a pool pole to the chlorine tablet holder if necessary.
Now brush those areas that were not removed by normal brushing with the chlorine tablet. What the chlorine tablets do is apply chlorine directly onto the black algae which penetrate into the roots of black algae which start killing them off immediately.
Clean The Pool Filter
Finally, clean the pool filter. You dont want any baby water boatman bugs, or bugs of any sort, dirt, and algae stuck in the pool filter.
Clean the pool filter after shutting it down. Take a cloth a soak it with dilute muriatic acid and scrub the pool filter with the cloth.
But itll be best if you change the pool filter and use a fresh and new pool filter to ensure no traces of water boatman bugs, their eggs, babies, and even algae are in the pool filter.
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Scrub The Black Algae Spots
No matter how well you just brushed your pool, youll probably still see some spots where the black algae just didnt come loose. Now you need to get up close and personal.
You can use a putty knife, a pumice stone, or even a hand-held wire brush to scrub the remaining black algae off the pools surfaces. We like to use chlorine tablets because now only do they offer a scrubbing surface, youre also applying chlorine directly, which can start killing the bacteria while you scrub.
For those spots you cant reach:
Dont worry if you dont get every speck of black algae off the pool surfaces because next youre going to
Why Is My Pool Water Yellow Or Orange
- This means that mustard or yellow algae is growing in your pool.
- This type looks like sand or pollen. It’s very sticky and adheres to pool walls that don’t get lots of sunlight.
- It is chlorine-resistant, very stubborn, and in some cases, it will grow even on pool equipment, toys, floats, or bathing suits.
- You cannot get rid of this type with a small amount of chlorine. You will need to deeply shock the pool using a high dosage of chlorine and clean all affected equipment with chlorine, as well. See instructions below.
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What Actually Causes Black Algae To Surface
If youve recently swam in a lake or ocean , then youre at risk of brining black algae into a swimming pool. From bathing suits to furry canine friends, transferring the algae is easier than you realise.
Black algae love filthy water, and it doesnt matter how much you keep proper chemical balance, if your filter isnt operating well, youre at risk. Check to see if your filter is clogged.
If it is, this could easily cause built up and encourage black algae to form. Cloudy water is another major tell tale sign, as it provides an ideal ecosystem to support black algae growth.
If youre at the point where you can see black spots on the surface of the water, youre too late, its taken hold.