The Best Pool Algaecide


The Best Pool Algaecide

Dealing with algae in your pool can be quite a headache, and it’s a challenge that many pool owners face. It’s one of those issues that often creeps up unexpectedly, turning your pristine pool water into a green, murky mess. Algae, with its fast-paced growth and stubborn nature, can really put a damper on your pool enjoyment.

Now, you might be thinking, “Isn’t chlorine enough to keep algae at bay?” Well, in many cases, chlorine does help, but it’s not always a silver bullet. Sometimes, you need an extra weapon in your pool maintenance arsenal, and that’s where algaecide comes into play. It’s not a magical solution, but when used correctly, it can work wonders alongside your regular pool treatment chemicals.

The dilemma faced by many pool owners today is choosing the right algaecide. If you’re a new pool owner, you might be scratching your head, wondering where to start. That’s where we come in! Our mission is to provide you with valuable guidance on selecting the best pool algaecide. Rest assured, with our recommendations, you won’t go wrong.

But before we dive into our algaecide recommendations, let’s take a moment to understand the basics. It’s crucial to grasp the different types of algae and the various algaecide options available to make an informed decision that will keep your pool sparkling clean.

What Is Pool Algaecide?

An algaecide is a chemical used to combat algae growth on the pool wall, floor, pool ladder, and even in the pool water. Most of the agents previously used as algaecides – e.g. those based on atrazine or dichlorphen – are now banned because they can accumulate in the water in the food chain and are then found in high concentrations in fish.

The same also applies to algaecides based on heavy metals such as copper sulfate or copper chelate. The use of these copper-containing algaecides has long been banned in running water, lakes, and ponds, but they are sometimes still used in swimming pools.

Instead, algaecides based on benzalkonium chloride, sodium carbonate peroxyhydrate, or aluminum chloride hydroxy sulfate are mainly used today in both public and private swimming pools.

How Algaecides Work

Algaecides attack and kill the algal cells by breaking down the cell walls, destroying the chlorophyll, or attacking other cell organs. But in many cases, the exact effect has not yet been elucidated.

Algaecides alone are not a panacea for algae in the pool because dead algae disintegrate and otherwise decompose in the water. In doing so, phosphates are released, which serve as algae food for new algae.

Another group of chemicals is used to disinfect the pool water and thus prevent algae, bacteria, and fungi from settling in the pool. Otherwise, the pool can turn green in no time, and swim time would be over.

This makes it clear that having a bacteria and algae-free pool in the long term can only work if there is an interaction between;

  • Algaecides to kill the microorganisms
  • Disinfecting chemicals such as pool chlorine to prevent new infestations
  • Mechanical means for detaching and sucking off the dead microorganisms.

Types of Algae

The following types of algae are most common in pools:

Green algae

Green algae are by far the most common type of algae in swimming pools. They get into the pool if toys or bathing suits are not thoroughly cleaned after swimming in lakes or rivers, thus carrying the algae. Green algae make pool water greenish. The color tone is more intense when there is a heavy load of algae.

The spherical green algae of the genus Chlorella are among the most common floating algae in freshwater. They are kept in suspension by gas vacuoles or stay in the water with hovering appendages.

The green algae of the genus Scenedesmus, which are also common in freshwater, form aggregates of 4 cells, each with long floating appendages

When they multiply in large numbers, green algae form large aggregates that collect on the water’s surface as slimy, green algal blooms. It must not come to that! At the latest, when the water in the pool turns green and cloudy, you have to intervene.

As filamentous colonies, while growing on the walls and the pool floor, they look disgusting slippery, and can make one slip.

Cladophora algae are also one of the most common filamentous green algae found on the water surface. They either form a thin film or clump together to form a cotton-like mass of algae.

Blue-green algae

These algae are not algae but bacteria, and they lack the cell nucleus. However, like algae, they drive photosynthesis with chlorophyll.

However, this green chlorophyll is masked by blue and red color pigments. This is why they do not look green like the common algae but rather blue-green with a metallic sheen.

These algae can absorb carbon dioxide for photosynthesis – these are the harmless ones. But there are also blue-green algae that release toxic sulfur compounds into the water instead of oxygen. The third group of these algae excretes toxic ammonia and ammonium.

This is how it starts: The tiny blue-green algae of the genus Microcystis clump together to form cell aggregates, clump together and then form algae wads.

While algae blooms are primarily an aesthetic issue, a mass colony of these algae is an assault on our health. It is not without reason that lakes are closed for bathing when there is a mass increase in blue-green algae.

If there is a blue-green alga bloom in the swimming pool – e.g. if the pool has not been used for a long time and the water has not been cleaned and filtered – then immediate action must be taken. In this case, thorough mechanical cleaning and subsequent shock chlorination of the water are essential!

Black beard algae

Black beard algae don’t appear a lot in swimming pools because it wouldn’t get to the point of having black algae infestation in a well-maintained pool. They are the most problematic type of algae. Difficult to remove, you must perform mechanical cleaning combined with chemical action to get rid of pool algae.

Sometimes they are also referred to as black algae, although they belong to the red algae. However, they can form part of the algae growth on the pool walls and cause long-term damage to the concrete wall with their roots.

Therefore, they must be removed thoroughly: It is best to kill them with black algae chemicals, loosen them with a steel brush, scrape them off, and then vacuum them off with a hand-held pool vacuum.

Yellow algae or mustard algae

Yellow algae (scientific for Xanthophyceae) are the closest relatives of green algae but have a slightly different composition of color pigments; that’s why they look more yellowish than green. Mustard algae in the pool occur less frequently, are more persistent, and are difficult to remove.

These yellow or mustard algae first settle in the biofilm, grow on the pool walls and multiply into a slimy, yellow mass. Then they gradually detach themselves from the walls and turn the pool water yellowish.

But it must not come to that in the first place because they cannot be combated with the usual chlorine-based algaecides. In addition, these mustard layers also survive outside of the pool and can settle on pool accessories, platforms, and ladders.

Therefore, thorough, mechanical cleaning and vacuuming of the pool walls are all the more important.

Our Top 3 Recommendations

Overall Best Pool Algaecide – Clorox 32 oz Pool & Spa Algae Eliminator²

Runner Up – HTH 67032 Super Algae Guard 1 Qt Swimming Pool Algaecide

Best Quality – Clorox Pool & Spa 43128CLX 42128CLX Pool Algaecide

Best Pool Algaecides: Our Top 10 Pick

Some of the best pool algaecides on the market are listed and reviewed below. But first, take a look at our top 3 selections.

1. Clorox 32 oz Pool and Spa Green Algae Eliminator² – Overall Best Pool Algaecide


Clorox isn’t new to formulating pool chemicals. Their Pool & Spa Algae Eliminator is a non-foaming formula and is ideal for all pool types, whether salt or chlorine.

This formula works efficiently on green algae, the most common algae type. Moreover, it does not take much. You only need some ounces in a normal-sized pool.

The fast-acting formula is ideal for preventing and killing algae and leaves the swimming pool water crystal clear.


  • Non-foaming formula
  • Effective for killing and preventing algae
  • Suitable for saltwater pools
  • Kills green and yellow algae
  • Ideal for all pool types


  • The chemical smell

2. HTH 67032 Super Algae Guard 1 Qt Swimming Pool Algaecide – Runner Up


The HTH Super Algae Guard is a pool algaecide that is ideal for use if you are fighting less ordinary algae like the black algae or yellowish algae. It will also eliminate and prevent ordinary algae but is intended to fight stronger algae problems.

In addition to being more powerful than many other algaecides, the HTH Algae Guard is a superb preventative treatment which will last up to 90 days following treatment. Yet it is safe to bathe in the water 15 minutes after application. You only need about 1 fluid ounce for every 10,000 gallons of pool water.


  • Works for more stubborn algae
  • Good for algae prevention and elimination
  • Has built-in clarifier
  • Fast-acting
  • Ideal for all pool surfaces and all types of algae
  • You can swim immediately


  • Foams a bit
  • Strong chemical smell

3. Clorox Pool and Spa 43128CLX 42128CLX Pool Algaecide – Best Quality


Oftentimes, when dealing with algae, it’s also advisable to use some clarifier to keep the pool clean. Clorox’s Pool & Spa Algaecide does everything. It’s a 2-in-1 product that kills algae and clears pool water.

Similar to the first Clorox algaecide reviewed earlier, the product is safe and ideal for all pool types, including spas. It is salt pool compatible. The algaecide ensures that the swimming pool is clear for weeks.

The Clorox Pool Spa algaecide and clarifier is also ideal for green algae. It does a wonderful job removing cloudiness that all these seaweeds can cause.


  • A 2-in-1 product; algaecide and clarifier
  • Provides exceptional algae control power
  • Improves pool’s water quality
  • Long-lasting effects
  • Salt pool compatible


  • You need more of the formula to get good results

4. McGrayel Algatec 10064 64-Ounce Super Algaecide for Yellow, Green, and Black Algae


The Algatec 10064 is a super pool algaecide from McGrayel. The name may not be familiar to you yet, but their superb algaecide packs a lot of punch. The formula works with other chemicals without throwing the elements off balance.

The non-foaming algaecide uses biostatic inhibitors to prevent dead algae from growing again or creating new algae blooms.

Algatec will even kill all kinds of algae and pests, interacting with the chlorine to protect and sanitize. It’s ideal for fighting green, black, and yellow algae. Plus, it works as a clarifier that leaves the swimming pool sparkling clean.


  • Doesn’t interfere with pool water pH
  • Uses biostatic inhibitors to prevent algae regrowth
  • Ideal for all types of algae
  • Non-foaming formula
  • Superior algae fighting power


  • You may need the whole bottle for each treatment

5. Clorox Pool Spa XtraBlue Pool Shock


The third Clorox Pool & Spa product on our list, the Pool Spa XtraBlue algaecide is an algaecide combined with bactericide. The pool shock is more of a very powerful biocide than anything else.

The Pool Spa XtraBlue algaecide should be used in swimming pools where aggressive treatment is needed, and the pool cannot be used while pool shock treatment is being applied.

You will see results in the very first week, and you can enter the pool water 15 minutes after adding the algaecide. The price of the Clorox Pool Spa XtraBlue is the highest of all the products here so far, although it is quite understandable why it’s a bit pricey.


  • Powerful chlorine shock treatment
  • High impact algaecide and bactericide and fungicide
  • Improves filter performance
  • Ensures pool is ready in 15 minutes


  • Algaecide action reduced by sunlight

6. Kem-Tek Pool and Spa 60% Concentrated Algaecide


The Kem-Tek Pool and Spa Algaecide model does’t just eradicate algae. Additionally, it also prevents potential infestations. It is the strongest polymer algaecide for use in the pool, so it’s ideal for algae that are immune to chemical treatments.

Since it’s so powerful, however, you need to be careful. The pool and spa algaecide has 60% algaecide concentrate and contains ethylene dichloride which is hazardous to humans and animals, according to the EPA and the label on the product.

Follow manufacturer’s application instructions and do not swim in the pool until it is fully circulated.


  • Algaecide compatible with salt system
  • Stops algae growth and prevents regrowth
  • Also clarifies pool water


  • Hazardous to humans and animals

7. In The Swim 1/2 Gallon Super Pool Algaecide


The In The Swim Super Pool Algaecide lives up to its name. The algaecide is highly concentrated and super effective at removing all kinds of algae in all kinds of water. Formulated to prevent the pool from staining, the swimming pool algaecide contains 7.1 percent of Chelated Copper.

The active ingredient in this algaecide is aluminum, which has proven to be a fast and powerful substance in killing algae spores and preventing expansion. However, the same ingredient can make it unsafe for drinking, so make sure you’re only applying the chemical in only with the one you’re swimming in!


  • Specially formulated for controlling mustard algae
  • Non-foaming formula, no-smell algaecide
  • Prevents pool wall staining


  • Not sold in California

8. Pool RX 101066 6 Month Algaecide Treats 20k-30k gallons

 The Pool RX Black Unit is an algaecide item that can simply be placed in a skimmer basket or a pool pump basket for eliminating all algae types. It simplifies spa and pool maintenance for up to six months.

The Pool RX mineral technology is ideal for all chlorine, salt, UV, and ozone systems. It ensures crystal clear water with less use of chemicals. The black pool unit is registered by the EPA and has an NSF/ANSI 50 certification. The pool algaecide supports 20,000 to 30,000 gallons of pool water.


  • Doesn’t stain pool surface
  • Ideal for eliminating all types of algae
  • Also suitable for salt pools
  • Turns green pool to clear pool
  • Simple to install
  • Helps balance pool chemistry


  • You may start getting algae in your pool in 30 days

9. Pool RX 6 Month Blue Algaecide for Treating 7.5k to 20k Gallons

Pool RX again sets the record with its Blue algaecide solution. This is similar to the Pool RX 101066. However, it can only treat smaller pools with a capacity of around 7,500 to 20,000 gallons. Why it’s different is that it’s powerful on all kinds of algae, such as green, mustard, and black algae.

It’s also incredibly powerful, fast, and user-friendly. Reviewers say they can simply drop the item and dive straight into a completely clean and clear pool in a day. It’s said to be effective in swimming pools for 60 days.


  • Turns a green pool crystal clear between a day to three
  • Ideal for saltwater pool
  • Ensures crystal clear water


  • Does not last for 60 days but it’s very effective

10. SeaKlear 90-Day Pool Algaecide for Algae Prevention and Removal

SeaKlear provides a 90-day warranty with its algaecide, which means you won’t find other algae in your pool for three months or more. This is, of course, assuming you follow the instructions and use them correctly.

This product contains aluminum, so it is powerful from blue-green, green, black, black, and mustard algae. Plus, it won’t foam or stain your pool surfaces, no matter which pools type you have.

The blue liquid pool algaecide is reliable and effective and comes with a 90-day no-algae guarantee. It contains 11.8 percent copper sulfate pentahydrate and 3 percent copper.


  • 90-day no-algae guarantee
  • For killing and preventing yellow, green, and black algae
  • Doesn’t foam or stain the pool


  • Not so effective for black algae

Frequently Asked Questions

Is algaecide harmful to humans?

There are some chemicals used in pool algaecide that are harmful to humans and animals. Most algaecides are harmful when swallowed or they get absorbed through the skin. However, when used as instructed, there is usually no cause for alarm. So, ensure you avoid breathing the vapor or letting the chemical come in contact with the skin or your clothing.

Can algaecide stain pool?

Copper-based algaecides can cause your pool walls to get stained. Meanwhile, quat pool algaecides can cause damage to your pool filter. That’s why you should buy a non-staining and non-foaming algaecide.

Does pool algaecide expire?

While swimming pool algaecides have a high shelf life, they are always viable for up to 5 years. But it’s always recommended that you only purchase what will sustain your pool for a season and the off-season period.

How much algaecide do you need?

For every 10,000 gallons of swimming pool water, one fluid ounce of swimming pool algaecide is sufficient.

Is too much algaecide in pool dangerous?

Applying too much pool algaecide can cause your pool to be foamy. If you’ve dropped too much algaecide into your pool, the solution would be to add more water to the pool to thin out the excess algaecide solution.

Factors to Consider When Buying Algaecides

There are several criteria to consider before selecting the best pool algaecide for you. However, the type of algae you are dealing with is one of the most important considerations.

Pool algae type

You’ll notice that some of the products in the review contain aluminum, which can be a powerful ingredient for black algae, as well as many others which are tough to eliminate.

The formula will also knock other algae out, but it might be a harder compound than you want if you’re just working with common algae. However, most of the other algaecides are based in ammonia, ideal for ordinary pool algae or quite tiny infestations, but they work ideally on yellow algae growth. Of the tens of thousands of species of algae, swimming pool masters only have to deal with a few species in 99% of cases.


Cost is always a criterion to consider for everything we buy. However, most swimmers’ pool algaecides are incredibly reasonably priced and last a while.

For a relatively decent price, you can save yourself some headaches in the future.

Long duration

Also, start looking for a durable product. We generally only recommend those that will eliminate and protect against algae for 90 days at the least. But in case you have a strain that is harder to kill, you will often have to treat your swimming pool regularly and use it in shorter intervals anyway.

For freshwater or saltwater pools?

The best pool algaecides are compatible with saltwater, freshwater, and other types of pool water. It’s recommended that you purchase what works for your pool system for best pool performance and to prevent damages to your pool materials.

Without Stains

Non-foaming and stain-free qualities are really important factors for the majority of pool owners using algaecides. The formula with copper contents can sometimes get your pool stained, but this can be unavoidable if you are dealing with a tough infestation.


Finally, determine if you want the product to include a clarifier. Many algaecides will turn the water a bit cloudy following application. An algaecide with clarifying action will leave your pool crystal clear after treating the pool algae infestation.


Maintaining a pristine swimming pool, free from the relentless intrusion of algae, can pose an ongoing challenge. Yet, diligent care and the strategic use of our premium pool algaecides can transform this daunting task into a breeze, resulting in a sparkling clean pool and significantly reduced maintenance efforts.

For countless pool enthusiasts, the realization dawns that relying solely on chlorine may fall short in effectively curbing algae infestations, particularly if their pool has endured multiple outbreaks. Embracing the incorporation of an algaecide into your regular pool maintenance regimen emerges as the most potent solution to vanquish this persistent menace.

In summary, the quest for a picture-perfect pool experience is marked by the unwavering commitment to combat algae, and our exceptional algaecide products stand as the formidable ally in this relentless battle.

Wise Reviewer

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