Pool Sanitizers, Oxidizers and Disinfectants

Before we go too deep, let me say first-off, if your pool looks blue and clear, and you have tested for good water balance and a normal (2-4 ppm) Free Available Chlorine level, your swimmers are most likely safe from pathogens, like bacteria and viruses.

According to this CDC document; “There is no evidence that COVID-19 can be spread to humans through the use of pools and hot tubs. Proper operation, maintenance, and disinfection (e.g., with chlorine and bromine) of pools and hot tubs should remove or inactivate the virus that causes COVID-19.” – Centers for Disease Control, March 10, 2020.

Many of our customers however, have increased chlorine levels in the pool, and are shocking the pool more frequently. We know this because sales for In The Swim chlorine have risen sharply in the last 30-days. Also more of you are choosing to stay at home (good idea), and buy pool supplies online this year (great idea).

Swimming Pool Sanitizers

A sanitizer is a chemical that will kill germs (bacteria, viruses, fungi and parasites) that could make you sick. Also defined as a chemical or process that will kill or deactivate 99.9% of bacteria on a surface or in a body of water.

Chlorine tablets and sticks are used to keep algae, bacteria, parasites and viruses from growing. You need a constant and consistent level of Free Available Chlorine in the pool, with a recommended pH level. The CDC recommends pH 7.2–7.8 and a Free Available Chlorine concentration of at least 1 ppm in pools and at least 3 ppm in hot tubs/spas.

In addition to a good pH (and Total Alkalinity) levels in the pool, to give chlorine the highest levels of efficacy (potency), don’t let the bright sun deplete chlorine levels during the day. The  Model Aquatic Health Code, or MAHC recommends a 30-50 ppm level of cyanuric acid, better known as pool conditioner or chlorine stabilizer. This minimum chlorine residual should be higher (2.0 ppm pools / 3.0 ppm spas), if the Cyanuric Acid level is higher than 50 ppm.

Biguanides are pool treatments such as Baquacil, Revacil or Aqua Silk, which are a class of sanitizer that do not contain chlorine, but rely on long-chain polymers as both sanitizer and antiseptic, and in higher concentrations, as a disinfectant.

Mineral Sanitizers, such as those created by Nature 2 and Frog, use the bactericidal properties of silver and copper ions to reduce contaminant levels, making the job easier for your main chlorine sanitizer.

Swimming Pool Oxidizers

An oxidizer is a chemical that steals an electron from another compound, thereby reducing the contaminant into their base components, and in the process, destroying them. An oxidizer is used to destroy organic contaminants, while a sanitizer is used to destroy pathogens such as bacteria and viruses that can make you sick.

Chlorine is both a sanitizer at low levels and an oxidizer at higher levels. For swimming pools, chlorine tablets, as the primary sanitizer, are the cheapest and most convenient way to add a consistent level of chlorine to the pool, all through the day, without creating peaks and valleys of chlorination.

Pool Shock however, is designed to dissolve rapidly and raise the chlorine level in the pool very high and very fast, to destroy organic and pathogenic contaminants. It’s called ‘Pool Shock’ because the chemical rips through the water very fast, like an electric shock. Available in 65% strength (Pool Shock), 73% strength (Super Pool Shock), and stabilized (Di-Zap).

Hydrogen Peroxide is another oxidizer that will steal your outer electrons when you’re not looking! A concentrated version of that used for swimmer’s ear and to dye hair platinum blonde, Hydrogen Peroxide also makes a great pool oxidizer when used with biguanide sanitizers such as Aqua Silk, for a complete sanitizer/oxidizer pool care system, as an alternative to tablets/shock. With this system, an algaecide is also used. Note: Do NOT use hydrogen peroxide in a chlorine pool, as it will remove the chlorine.

Non-Chlorine Shock is a class of potassium salts, sometimes referred to as MPS or as (potassium) monopersulfate, that is a granular chlorine-free oxidizer for pools and spas. Very effective as an oxidizer, but it does not raise the Free Available Chlorine level, or kill algae, and is not EPA registered as a sanitizer.

Swimming Pool Disinfectants

Whereas a sanitizer will kill 99.9% of bacteria strains, disinfected means a complete kill of 99.999% of pathogenic germs, including viruses, mold, bacteria and more. Disinfected surfaces or pools have been shocked very heavily, to destroy 100% of contaminants. The difference between sanitation and disinfection is the time it takes to achieve each level.

Consider Super-Chlorinating vs. Hyper-Chlorinating. “Super” is simply your normal shock treatment, added after the sun goes down, say to 10 ppm. By morning, the level has dropped to 5 ppm perhaps and by mid-afternoon, levels are down below 2 ppm.

Hyper-Chlorinating, on the other hand, is to raise chlorine levels very high, say to 20 ppm or higher, and hold it there, with continuous additions of sanitizer (shock), to maintain the high chlorine level for up to 24 hours of time, or longer based upon the water conditions. Hyper-chlorination is used for very difficult to eradicate protozoan parasites, such as cryptospridium or to a lesser degree, the giardia parasite.

Hyper-chlorination is not necessary for the removal of your everyday bacteria or viruses, even the Coronavirus. You can disinfect your pool in most cases, with the suggested dosage listed on the bag of pool shock oxidizer.


In The Swim is here for you during this pandemic, and is open to provide support and sanitizers to our customers in need. We’ve also lowered prices on the most commonly purchased pool sanitizers and oxidizers.

18 thoughts on “Pool Sanitizers, Oxidizers and Disinfectants

  1. Ok Patterson

    My grandson went swimming in our pool which had algae. It was treated 2 days ago but still has algae on walls. Will he be okay? Should we do anything? Thanks, PK

    • Hi, in all likelihood he will be fine. The algae is not a concern, it’s the bacteria that (may possibly) be in the pool, however it is unlikely that anything will come of it, especially if you had treated the pool with chlorine in the last few days. Just a little algae on the walls? I wouldn’t worry about that…

  2. Patricia Torruella

    Hello, Dr. Pool. I have a small 8 x 30 Intex vinyl pool in Puerto Rico, which in case you are not familiar with the island, it is in the Caribbean with tropical climate year round. I bought a “Solar Pool Ionizer” in order to avoid chemicals. Can you please comment on these ionizers? Thank you.

    • Hi Patricia, I am quite familiar, and actually I am visiting Cabo Rojo next month! The Solar Pool Ionizer is a good tool for your pool. In plaster pools, they have the problem of staining when overused, but not for vinyl pools. It will help sanitize the water with silver and copper ions. You will still want to use chlorine, to be sure the water is sanitary, but can use less, maintaining a 0.5-1.0 ppm level, with a good pH of 7.2-7.6. Put the ionizer on the low setting, and perhaps only use it a few hours per day, as they are made for much larger pools, and could easily over-dose your small pool, plus it will last longer if used only as needed.

  3. Peggy Long

    I am using Aquasilk products in my pool. I have a 15000 gallon pool. My water is cloudy and noticed this when I started heating our pool with an outdoor wood stove. I am trying to clear the water up. This is my first year of having a pool and learning. I tested my pool with aqua check free chlorine and this is my results ph 7.8 total alkalinity is 120 and my stabilizer is 0. Not sure out of the 3 products I am using what I need to put in to raise the stabilizer. The 3 products I have been using all summer is aquasilk shock, aqua silk sanitizer, and aqua silk algaecide.

    • Hi Peggy, stabilizer (cyanuric acid) is only used on chlorine pools, so you don’t need it. You can use a clarifier however to help clear the water, and should also look at the filter media (sand/cartridge/grids) in the filter, as using biguanide products will clog up your filter media in 1-2 seasons, requiring replacement.

  4. “Hi John, you can put a tablet into a bucket of water, and use the chlorinated water as a disinfectant, for other surfaces, yes. In this way, you can cheaply make your own disinfectant spray for example. The same can be done with Pool Shock, if you pour an ounce of shock into a gallon of water, you can create a strong disinfectant solution.”

    Would this be a good solution to disinfect/sanitize hard pool furniture and pool deck surfaces to kill any Corona left behind?

    • Yes, certainly. The easiest way would be to buy a $10 pump sprayer at your favorite Home Store, and fill it up with a gallon of water and add a small amount (2-4 oz) of granular chlorine, or 4-8 oz of liquid bleach, and you have a disinfectant solution. The pump sprayer will allow you to work much faster than a spray bottle. Even faster than the pump sprayer are the backpack sprayers.

  5. Richard Stiefler, M.D.

    So, should baquacil destroy cornoavirus as well as other viruses and as well as chlorine? Thank you!!

  6. Can chlorine tablet be used on other surfaces becid the pool

    • Hi John, you can put a tablet into a bucket of water, and use the chlorinated water as a disinfectant, for other surfaces, yes. In this way, you can cheaply make your own disinfectant spray for example. The same can be done with Pool Shock, if you pour a few ounces of shock into a gallon of water, for a disinfectant solution.

  7. Can I use granular chlorine to shock my pool on a weekly basis this summer? Or do I need to buy shock?

    • Hi Amy, granular chlorine IS shock, or the same thing. There are two main types of granular shock – dichlor and cal hypo. Dichlor is stabilized (with added cyanuric acid) and is 56% available. Cal Hypo is unstabilized and is 65% available, or 73% available, for our Super Pool Shock.

  8. Hi Davy, thanks so much for your reply. We did as you instructed and retested our water today.

    These are today’s results:
    Total Hardness- 250
    Total Chlorine- 5
    Free chlorine- 5
    PH- 7.8
    Alkalinity- 120
    Stabilizer-0

    So we went from no chlorine to it saying we are high now after the alkalinity increase and shock.

    Do you recommend we do anything else? We have a chlorine floater in the pool and have been running the filter non stop.

    • Hi Lacey, looking good! I would add a little bit of pH decreaser, to get the pH level down around 7.4, where the chlorine is more potent. The chlorine level will come down naturally in the next few days, if not already. If you are having trouble keeping a chlorine level, adding a small amount of cyanuric acid (Stabilizer) will help protect the chlorine from the sun. Just 1 lb. should do it, don’t want to over-dose, as it can cause other problems.

  9. Hello! We just set up a 12ft x 30 in intex prism pool yesterday. We did an initial shock and put in a floater with chlorine tablets.

    We tested the water today after 24hrs and it says the pH is 7.2, but chlorine is nearly 0ppm and the alkalinity and stabilizer are low.
    We’re first time pool owners… do we need to buy additional chemicals?

    • Hello, add some alkalinity increaser, just 1 lb should raise the level about 30 ppm, which will also raise pH a bit, and help it to stay stable. Stabilizer should be 20-30 ppm minimum, and 50 ppm max. Add another shocking of the pool today, and see if the chlorine level holds. You probably need just 1 3″ tablet, or maybe two, just enough to get a consistent chlorine reading of 1-2 ppm, as verified by your testing. If levels are too high, use less tablets, if levels are too low, add more, and remember to replace them promptly when they are almost completely dissolved. You must have a chlorine reading in the pool 24/7, from now until the end of summer. When chlorine levels drop to zero, algae and bacteria begin to flourish immediately, and within 48 hours can turn the entire pool green, costing lots of time and money. Also important is to run the filter nearly non-stop. If you try to save electricity, you will pay more in chemicals, and run the risk of problems with the water quality. This is especially true with the small filters that come with the Intex pool, just let it run all the time, or at least all day long, 12+ hrs daily, every day.

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