Pool School 116 Algae

Algae MonsterFront

Don’t Let The Algae Monster Get You!

Let’s start with a basic understanding of algae, because in order to win the algae battle we have to know what we are up against. There are three key points I want you to keep in mind during this class; first, alga (one single cell of algae) is a microscopic organism. You cannot see it without the aid of a microscope. Second, you always have algae in your pool, ALWAYS.  Third, algaecide by itself cannot cure an algae bloom.

So now we have the basic understanding I will get into more specifics. Please don’t take offense to the fact you always have algae in your pool water, it is just a fact of nature. Algae are everywhere and when your pool is exposed to the environment it will end up with algae. Which leads to the inevitable question; how do I get rid of all the algae in my pool? The simple answer is you don’t.   What you do with the pool chemicals, and filtration system, is you keep the growth under control so you cannot see it with your eye. Remember the first key point is alga is microscopic so you will not actually see it until it is way out of control. Algae found in pools is not harmful to humans, there are some forms of algae that people actually eat for protein. However, algae are unsightly (no one likes to look at a green pool) and when you dry off after having swum in an algae infested pool you will not like the feeling on your skin. In addition when the algae die they give off a horrible order that smells like three day old dead fish.

What is a pool owner to do to win the algae war? Your first line of defense is proper water chemistry and routine chemical testing and treatment. When I say routine I mean weekly checks and treatment if necessary. Your second line of defense is your filtration system, weekly you want to check your equipment to make sure it is working properly and the filter does not need backwashing. Your third line of defense is weekly cleaning the pool; this includes vacuuming the floors and/or brushing the walls of the pool. Your forth line of defense is an Algaecide. If you follow these simple rules in most cases you will successfully beat the algae, however circumstances may override your diligence and you may lose the battle, but you will not lose the war!

Now that we are engaging the enemy we need to know the enemy a little better. There are literally thousands of types of alga. In pools we are usually dealing with five basic forms; green algae, yellow algae (also referred to as mustard algae), pink algae, brown algae, and black algae. Each one of these enemy combatants has it’s own special characteristics and what we want to take as a weapon into battle will depend on this information. Let’s review the different types of algae:

First up is enemy number one green algae; the first thing we need to know is green algae prefers shaded sunlight. This helps us know where to look, because green alga likes to hide from you so that you will not find it until it is too late. Places you will want to look will be; the shaded side of the pool, underneath the ladder treads on your ladder in the deep end of the pool, and the most forgotten site, behind the underwater light. Your first wave in battling green algae is to brush it off of whatever surface it is clinging to. It is easier to kill the algae when it is in the body of the pool water because the chemicals cannot efficiently reach the algae when it is attached to something. Then you would vacuum the pool followed by a shock treatment along with either Banish® by Bio Guard or 90 Day Algae Preventer and Remover by SeaKlear.

Second up is the most difficult algae to get rid of, yellow or mustard algae; this alga requires a decontamination process to rid yourself of this enemy. Mustard alga will cling to stuff that ends up in the pool and subsequently introduce itself back into the pool later or into another pool. Classic case; I had a customer who managed an apartment complex. She came to my test lab and slammed her bottle down on the counter and said she just wanted to know one thing, “Can you get mustard algae from a test kit?” The answer is yes. To that she said that is what I thought. It seems the health department, three days before, had visited her pool for a routine surprise inspection. After the inspector tested the water the inspector made the comment of how nice her pool looked, the inspector said that every pool they had been to that day had mustard algae. I don’t think I need to say more. So to successfully get rid of mustard algae you will need to follow these steps; first, brush and vacuum the pool. Second, shock the pool (assuming you are using chlorine to sanitize your pool, if you are using something else consult with Aegean Pools before proceeding) using one pound of shock for every 10,000 gallons of pool water. If you have an odd number of gallons rounding up is a good idea. You will need to make sure your pH level is correct and possibly add additional pH adjusters, it is best to have the water professionally analyzed at Aegean Pools before proceeding. Third, add either Banish® by Bio Guard or 90 Day Algae Preventer and Remover by SeaKlear. Fourth, let the pool circulate overnight then the next day take anything that was in the pool while the mustard algae was in the pool and put it back in the pool for 20 minutes. By anything I mean anything; floats, toys, games, bathing suites, friends and neighbor’s bathing suites, your family’s bathing suites, pets, maintenance equipment, testing equipment, automatic pool cleaner, anything you can think of that had been in the pool. Fifth, take a buck of water from the pool and clean any deck furniture you may have sat in and clean it with the pool water. Sixth, take another bucket of pool water and clean the pool deck with the water from the pool. This should kill any residual of mustard algae and reduce the chances of getting it back again. However, once you have had muster algae you are always susceptible to getting it again, it can hide like a sleeper agent.

Third up on our least wanted list is a pink alga. This is actually a combination of both a bacteria and algae. As usual you will want to brush, vacuum and shock the pool then apply Back-Up® by Bio Guard.

Fourth up Brown alga; this algae usually is introduced from a salt water environment like a creek, the ocean and so on. The best treatment for this alga is the same as mustard algae (see second up on our list above).


Fifth and last on our list is black alga; this algae is a very stubborn algae, it actually secretes a waxy substance that protects it from harmful chemicals in the pool water. This alga loves little nooks and crannies and is more often found on concrete pools. To treat this algae we take the same first steps; brush, vacuum and shock. Then apply Algae All 60® by Bio Guard or Algaecide 60 from Pool Season. One more step in the removal process and that is brushing. When you brush the algae on a concrete pool that has a masonry surface you will want to use a stainless steel bristle brush, in a concrete pool that is painted, a fiberglass pool, or a vinyl liner pool you will want to us a plastic bristle brush so you don’t damage the surface of the pool. When you brush the locations where the algae is located you will only remove a small amount of the algae, the dead layer that the algaecide has help permeate. You will need to continue to brush the pool until you can no longer see the black algae, however you are not done brushing, remember algae is microscopic and you will brush it until you can’t see it any more but it is still there and if you stop brushing it will make a comeback in a few days. So you will continue to brush it for at least three days after you lose sight of the spots.

Rather than trying to combat algae after it has invaded your pool, let’s look at ways of preventing a full fledged war on algae. When it comes to preventing algae the king of this process is BorX by N. Jonas. BorX renders algae incapable of processing carbon dioxide, algae being a plant life exchanges carbon dioxide. So by blocking that process it suffocates algae. It does such a good job that it will substantially reduce the amount of sanitizer you use. If you want the Cadillac of algae prevention this is the King.

These three algaecides are good preventers you will use on a routine basis; Back-Up®, Algae All 60®, Algaecide 60, Banish®, or 90 Day Algae Preventer and Remover. Banish® and 90 Day Algae Preventer and Remover are also excellent killers.

One topic I am going to pass on is phosphates; if you have been in school and not skipping class (and you know who you are) you would have already learned about phosphates in Pool School 107. If you have not been to this class then you can review it on our Word Press blog.


One other thing I would like to cover today is an alternative use for Back-Up® Algaecide. This unique product helps prevent algae by making the water wetter. I know that sounds weird, but that is the best way to describe what it does. That process can help you eliminate spiders that float on the pool water and help keep ducks out of your pool. When spiders float on the pool surface they do so by creating an air pocket under them. Back-Up® takes the air pocket away and they end up sinking in the water like an ocean liner with a gaping hole in its hull. Ducks on the other hand will not sink, that would be messy, but duck feathers are covered in oil and they are designed to keep the water from coming into contact with their skin. Back-Up® making the water wetter allows the water to permeate the feathers and the water makes contact with their skin, the ducks will be doing a touch and go in your pool. They will learn that your pool water is weird and not to their liking and off they will go in search of a more friendly body of water.

So your battle plans have been drawn for you, time to suit up do some re-con then to battle! Good luck and don’t forget your best ally in your war against algae Aegean Pools Test Lab, our lab technicians are highly trained algae ninjas. Algae hates our test lab! Class dismissed until next time…don’t be late for class!


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