Biguanide Pool Treatments: How They Work

Written by Michael Dean
June 8, 2023

biguanide pool chemicals

When searching for the best pool treatment options, it can be overwhelming to consider the vastly different sanitization methods and products available. The most common pool treatment is chlorine. However, there are alternatives for people with sensitivities to chlorine.

Biguanide is a gentler pool treatment option that may be ideal for certain people, but there are several factors to consider when choosing a pool treatment. So, let’s look at all the details to determine if biguanide is a good pool treatment option for you.

Main Takeaways

  • Biguanides cause contaminants in the pool to clump together and easily be filtered out by your pool filter.
  • Biaguanide is gentler and less irritating than chlorine, so many swimmers that are sensitive to the effects of chlorine opt for biguanide.
  • Biguanide is also stable in UV rays, unlike chlorine which breaks down in the sun.
  • You will have to purchase other chemicals to use alongside biguanides as it doesn’t protect against all issues.

What Are Biguanides, and How Do They Work?

Polyhexamethylene biguanide is a bit of a mouthful. It is more commonly called biguanide or PHMB for short. This chemical is a chlorine-free sanitizing solution that acts as a biocide. You can find this ingredient in cosmetic products, contact lens disinfectants, food handling or agriculture cleansers, and pool sanitizers.

Chlorine and biguanide can keep your pool clean and sanitary by dramatically different methods. Biguanide works by causing pool contaminants to bind together into clumps that are easy for the pool filter to catch.

By nature, this means you’ll need to clean out your filters more frequently to prevent them from filling with these clumped contaminants. More frequent cleaning is a small price to pay to ensure no unwanted pollutants remain in your pool.

Biguanide Pool Chemistry

Regardless of the pool treatment you use, you’ll always need to monitor the chemistry and balance of your water. Regular maintenance and testing help avoid bacterial infections or contaminants resulting from unsanitized or improperly sanitized water.

In the instance of a biguanide-based pool treatment, biguanide is your sanitizer. The sanitizer levels in your pool have the most considerable impact on your water quality. For maximum protection, your sanitizer should stay somewhere between 40 ppm and 50 ppm. Sanitizer levels should never go lower than 30 ppm to ensure a safe swimming environment.

Additional Products

An oxidizer is different from a biguanide sanitizer, and you’ll need to add an appropriate oxidizer when you use biguanide as your pool treatment. This treats organic or product contaminants in your pool water, such as sweat, oils, soaps, makeup, or urine. Oxidizers also improve the sanitizer’s effectiveness against algae.

The most popular biguanide chemical brand is Baquacil, and I definitely recommend their products for this type of pool system.

Regarding algae, since biguanide is not an oxidizer, it isn’t able to prevent algae formation on its own. If you’re using a biguanide pool treatment, you’ll want to keep a compatible algaecide on hand to prevent algae growth.

Other Levels to Monitor

Every time you adjust something in your pool, you should test the water levels to ensure everything is in order. Your water’s acidity or pH levels should remain in an ideal range of 7.4 to 7.6. A pool pH level that is either too high or too low can cause irritation or reduce the effectiveness of the pool treatments you are using.

To help maintain stable pH levels, you’ll also need to monitor your alkalinity. Ideally, this should measure at 125 ppm, with a safe range between 100 ppm and 150 ppm. Alkalinity is your pool’s buffer to keep pH levels stable.

You can adjust alkalinity by using a product designed to increase or decrease alkalinity. Alternately, adding sodium bicarbonate will raise alkalinity, while muriatic acid can lower it. The easiest way to lower alkalinity is by waiting for the levels to decrease over time.

Calcium is needed to prevent pool water from causing deterioration of your pool. Low levels can cause damage to metal or concrete that comes into regular contact with the water. A high concentration of calcium can lead to a cloudy pool. You want to keep levels between 175 ppm and 275 ppm.

Pros of Biguanide Pool Treatments

The gentle sanitation you get with a biguanide pool treatment is one of the primary reasons people switch to chlorine treatments. Chlorine has a reputation for being a mild irritant, and for some people, it can be pretty severe.

While you can’t exactly be allergic to chlorine, you can have a sensitivity to it which can cause effects similar to a mild chemical burn. Certain health conditions can respond negatively to chlorine as well. Biguanide does not cause the common irritation from chlorine and can be a game-changer for those with sensitive skin.

It’s no secret that the nostalgic smell we commonly associate with a swimming pool results from the chlorine treatments used. What is less known is that the scent is not the chlorine itself but the chloramines that get released as a reaction between the chlorine and organic substances. Since there is no chlorine in a biguanide-based treatment, there will be no chloramine production, and therefore, no “classic” pool smell.

Biguanide is light-stable, unlike chlorine which slowly degrades when exposed to sunlight. Considering most pools are outdoors and regularly in the sun, much of the chlorine you add to your pool degrades, meaning frequent additions are needed. You can count on biguanide levels not lowering due to sunshine or heat.

Chlorine pools tend to leave your hair feeling crispy and a bit lifeless. It can also be devastating to hop in the pool with pale blonde hair to come out an hour later with a minty green hue. The opposite can also happen with freshly dyed hair that fades after a quick swim.

Most processes applied to hair use oxidation to achieve the desired results. As I discussed above, biguanide is not an oxidizer, meaning it’s gentler on hair. If you or a family member regularly color their hair and love to be in the pool, biguanide may make all the difference in how long the colors last.

Cons of Biguanide Pool Treatments

Any pool system has pros and cons, and some of the best aspects also have considerations to keep in mind. It’s time to address the drawbacks of biguanide pool treatments.

You’ll first notice that biguanide is not an all-in-one treatment. It cannot rid your pool of all possible contaminants, thus requiring supplemental products. In the end, you’ll need the biguanide treatment, oxidizer, algaecide, alkalinity and calcium control products, and testing supplies for each parameter.

Pair the need for multiple products with the higher price tag, which may be out of budget for some people. It may not be vastly more expensive, but the slight increase can add up over the life of a pool.

As is typical with antibacterial products, biguanide can become ineffective against some bacteria after prolonged use. Certain microorganisms can develop a resistance to biguanide which can diminish the sanitizing effects with long-term use. In severe cases, this resistance can lead to the formation of water molds or pink slime.

Some side effects of biguanide use can be cloudy or foamy water resulting from the biguanide clumping with contaminants. Luckily these can readily be resolved by regularly cleaning the pool and cleaning the filters.

Is Biguanide a Viable Alternative to Chlorine?

Biguanide can be a tremendous alternative pool treatment if you or a family member have sensitive skin or health issues that flare up from chlorine exposure. The same is true if you or your family regularly have color-treated hair.

Biguanide is a solid alternative to chlorine when paired with the correct combination of products. It’s important to compare the pros and cons as they relate to your specific situation to determine if this pool treatment system is right for you.

Converting Your Pool to Biguanide

The best time to get the transition done is early in spring when you’re preparing for the year ahead. Luckily, you won’t need to fully drain your pool to make the switch. Converting your pool from one system to another can seem daunting, but I’ll break it down into easy-to-follow steps.

How to Convert From Chlorine to Biguanide

Start by replacing your pool’s filter itself or the filter materials, such as sand or diatomaceous earth. This will give you a clean slate and ensure no residual chlorine in your filter system.

Apply a reducing agent to your pool to lower the levels of chlorine. Be sure to run the pool long enough for all the chlorine to neutralize. If needed, you can add more neutralizers if chlorine levels are higher than zero.

You will then add the sanitizer, oxidizer, and algaecide products as specified until reaching the required levels. Once your tests show the correct levels are stable, your pool is ready to be enjoyed.

You’ll need to check the levels of the biguanide sanitizer and your additional products weekly to avoid swimming in unsafe water. Shocking the pool will be needed from time to time to eradicate organic buildup. Luckily a hydrogen peroxide shock only shuts down swim time for about 15 minutes.

How to Convert From Biguanide to Chlorine

The transition from biguanide back to chlorine follows most of the same steps, simplifying things if you ever decide to switch back. It is nice to know a change isn’t permanent, and you can freely experiment with a biguanide pool treatment without much to worry about.

This process begins by waiting for the existing biguanide levels to reach zero. Stop adding your biguanide products and test the water as it decreases until no more is detected. To prevent algae during the waiting period, you can use an algaecide not based on biguanide.

Your next step is replacing the filter or filter medium for your pool. There are some products available designed to clean filters to avoid replacements. However, when switching the whole pool system, it’s best to replace the filters entirely. Not doing so can leave behind traces of the previous chemicals that can interfere with your entire system’s effectiveness.

Now that the pool is free of all biguanides, you need to adjust your alkalinity to acceptable ranges. Once alkalinity is stable, you’ll adjust pH. You can continue to the next lengthy process once both of these are reading at the correct levels.

Your pool needs to be shocked using non-chlorine shock. After adding this, it’s important to run your filter for 48 hours while allowing the transition to complete. When the time is up, check your pH again and adjust if needed to maintain the desired levels.

The final step is adding the chlorine back into the system, following the instructions on your selected product for the best results. When all the product has been incorporated, test your levels for a final time, making any further adjustments.

From here, you continue regularly maintaining your pool as normal for chlorine pools.

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Final Thoughts

The type of pool treatment products you decide to use can vary greatly based on the specific features you want for your pool. If your pool budget allows for the higher product cost, and you don’t mind a little extra maintenance work, then biguanide-based sanitizers can be well worth the benefits they offer.

People who aren’t fond of the strong smell of chlorine or eye irritation may enjoy the gentle aspect of biguanide systems. The transition is also well worth it for people with a sensitivity to chlorine.

Biguanide systems offer some great benefits, but they aren’t for everyone. This can be the case if you don’t have a chlorine sensitivity, easily fading hair color, or a health condition that worsens with chlorine. You may also prefer a chlorine system if you don’t want to spend extra time and money on regular maintenance.

In the end, there are many facts to consider and different features to weigh when deciding which system is best for your pool. No matter what products you choose, your pool needs regular maintenance, cleaning, and testing to stay in tip-top shape. It’s up to you to choose a system that will meet each of your needs reliably.

Questions on biguanide systems? Drop me a line.

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