Biguanide Pool Treatment: What It Is & How to Use It

Biguanide Pool Treatment


Chlorine is the number one swimming pool cleaning and sanitizing agent, but it is not the only option as there are still many other good ones like biguanide.

Biguanide cleans and sanitizes the pool as effectively as chlorine and sometimes even better. Also, it is often a gentler option than chlorine and will be a more appropriate option than the latter for some situations.

That said, it is essential to have a good understanding of this pool chemical as this allows you to make an informed decision on whether it suits your particular situation.

What is Biguanide? 

Biguanide or polyhexamethylene biguanide (PHMB) is a chlorine-free cleaning and sanitizing agent in the same chemical family as peroxide to bleach. The compound is also an antiseptic with antibacterial and antiviral properties, making it very effective at cleaning and sanitizing.

Unlike chlorine, biguanide will not kill the pool contaminants, given that it does not produce any harsh elements like hypochlorous acid capable of attacking the bacteria or algae cells.

Instead, it forces the contaminants to bind together and form insoluble clumps that are easy for the pool’s filtration system to capture when cleaning the water.

Therefore, when using biguanide, you need to clean the filter more often as there will be an increased accumulation of clumped contaminants.

Benefits of Biguanide Pool Treatment 

Although biguanide does not address all problems that come with chlorine pool treatments, it solves most of them and has many other benefits that every pool owner needs to know.

1. Zero Chloramines Production

Biguanide does not lead to the formation of chloramines. The accumulation of chloramines over time is one of the most significant shortcomings of using chlorine to clean and sanitize your swimming pool.

Chloramines form when chlorine binds to the body waste that swimmers release like sweat and urine. They usually give off a strong chlorine smell and can irritate the eyes, skin, and respiratory tract.

Since there is no chlorine in biguanide, there is nothing to bind with sweat and urine to form chloramines, and it also does not give off any other harmful by-products.

2. It is More Stable

Pools that use chlorine require you to add more now and then, given that it breaks down quickly under the sun as it is not very stable. Adding pool stabilizer (cyanuric acid) often helps make chlorine more stable, but you never have to go through all that trouble with biguanide.

Biguanide is a more stable sanitizer that does not break down easily even under direct sunlight. Hence, you will not need to keep adding more as frequently as chlorine, saving you money and time.

3. It is Not Harsh on the Pool’s Fixtures

Biguanide will not react with metal fixtures in the pool and damage them through oxidation. Also, unlike chlorine, it does not bleach things like the pool’s vinyl lining or even the swimmers’ swimsuits as it is not a harsh compound.

When not to Use Biguanide

If you are looking for a highly effective sanitizer that can kill all kinds of contaminants, biguanide will not be ideal for you.

Chlorine comes close to killing all contaminants in the pool. However, biguanide is not effective on things like sweat, sunscreen, and body oil unless you use it with a combination of other products.

Additionally, over time biguanide becomes ineffective against some microorganisms. Like with most other antibacterial products, these microorganisms develop resistance against biguanide. Hence, you should avoid using this pool sanitizer for prolonged periods.

You should also not use this sanitizer if you are looking for something more budget-friendly as it is more expensive than chlorine. If you also factor in the fact that you need to use it with various other products like algaecide and oxidizer, it becomes even more expensive.

How to Use Biguanide Pool Treatment

If you have been using chlorine to treat your pool, here are few steps to follow if you want to use biguanide.

Step 1: Start by Replacing Your Filters

The first step should be filter replacement to ensure you will not have any chlorine residue in the filtration system.

Step 2: Apply a Reducing Agent

Next, apply a reducing agent to the pool water to remove any other sanitizing agents like bromine and chlorine in the water.

Step 3: Run the Pool for 8 to 12 hours

You should then run the filtration system for at least 8 hours and then recheck the sanitizer levels. If there is still chlorine or bromine present, you need to add more reducing agent and repeat the process. Make sure you do not add any biguanide until the sanitizer levels are zero.

Step 4: Add Biguanide, Algaecide, and Oxidizer

Once you are confident that the sanitizer levels in the pool are zero, you can add the biguanide, algaecide, and oxidizer. Follow the manufacturer’s instructions here and make sure you attain the recommended levels.

Biguanide vs. Chlorine (Pool Treatment)

Both biguanide and chlorine will clean and sanitize the pool water. However, biguanide only removes bacteria, while chlorine deals with several kinds of contaminants from bacteria and algae to organic matter.

When using biguanide, you also need to add an oxidizer to enhance its effectiveness, but chlorine is potent enough without adding anything besides a stabilizer to prevent breakdown.

Like chlorinated pools, those that use biguanide need to maintain a pH level of between 7.4 and 7.6. Additionally, calcium hardness and alkalinity levels are also crucial when using both pool sanitizers.


Biguanide is a good chlorine alternative for pool owners looking for a more stable sanitizer that will not be harsh on fixtures or the swimmers.

If you use it with other things like algaecide and oxidizer, you can match the effectiveness of chlorine in cleaning your pool. However, you will not know whether it is a viable alternative for you or not until you give it a try.

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