Common Pool Chemicals

Below is a list of the most common pool chemicals you will use in and around your swimming pool. For clearer reference, we list the common names, general use, physical form, and active ingredient names for each entry.

Water Balancers

pH Increaser (Sodium Carbonate, Soda Ash)
-Increases the pH of the pool water
-Most commonly found in powder form, but available in liquid
-Common Names: pH Up, pH Rise, pH Increaser

pH Decreaser (Sodium Bisulfate)
-Lowers the pH of the pool water rapidly while lowering alkalinity slightly.
-Most commonly found in powder form, but available in liquid
-Common Names: pH Down, pH Decreaser

Alkalinity Increaser (Sodium Bicarbonate, Baking Soda)
-Raises the Alkalinity of the pool water with little to no adjustment to pH.
-Available in powder form
-Common Names: Alkalinity Up, Alkaline Rise, Alkalinity Increaser

Alkalinity Decreaser (Muriatic Acid, Sodium Bisulfate)
-Acid lowers pH while also lowering Total Alkalinity, so pH will need adjusted once the Alkalinity has been treated.
-Sodium Bisulfate is commonly known as pH Decreaser, but when used in larger quantities, it makes an effective chemical in controlling Total Alkalinity as well.
-Muriatic acid is a popular chemical used to lower Total Alkalinity. It is a dangerous chemical if mishandled, and should be used with caution. If handled properly and used properly, it makes sense economically. It takes less muriatic acid per volume of pool water to adjust pH and Alkalinity than it does sodium bisulfate (pH Reducer).
-Available in liquid form (muriatic acid) and powder form(sodium bisulfate). Consult your local pool dealer for information if you are looking for alternatives that are effective and even safer to use.
-These are strong acids. Use extreme caution when using these pool chemicals and as with any pool chemicals, read and follow label instructions, warnings, and storage procedures.

Calcium Hardness Increaser (Calcium Chloride)
-Increases the Total Hardness of pool water
-Available in granular form, as well as a relatively new liquid form.
-We recommend only adding 1/3 of the required dose with 2-4 hours in between doses when adding Calcium Hardness Increaser to your swimming pool.

Sanitizers

Arguably the most important of all pool chemicals, sanitizers control bacteria and algae growth. They greatly reduce the risk of viruses and other microorganisms, as well as help to maintain water clarity.

Chlorine
-Most widely/commonly used pool sanitizer.
-Found in liquid, granular, and tablet form. Tablets are easiest for establishing a constant supply of chlorine, while the other two forms serve best as shock treatments. Chlorine can also be generated through a chlorine generator, or Salt System.
-If the pool is outside and exposed to a lot of sunlight, the use of stabilized chlorine may be necessary. Cyanuric Acid, also known as Stabilizer, helps to keep chlorine from breaking down in UV light. This chemical is found in stabilized chlorine tablets and some granulars.

Bromine
-Available in tablet and granular form.
-Considered to be softer on swimmers than chlorine.
-Is very sensitive to UV light so it dissipates quickly if the pool is exposed to a lot of sun. Due to the need for constant replenishment, a pressurized feeder called a brominator should be used to slowly supply the pool with bromine.
-Although expensive in comparison, bromine is more effective at killing algae than chlorine and is just as effective at killing bacteria.

Biguanide (PHMB, short for Polyhexamethylene Biguanide)
-Completely Chlorine and Bromine free.
-Incompatible with some pool chemicals, particularly chlorine and bromine.
-Considered to be one of the most swimmer friendly sanitizers available.
-Effectively kills bacteria and algae in pool water.
-Remains in the pool water longer than most other sanitizers, making it easy to maintain.
-Requires the use of a hydrogen peroxide based oxidizer as part of its weekly upkeep

Ionization
-A natural alternative to traditional pool chemicals.
-Uses copper and silver to kill bacteria, viruses, and prevent algae.
-Only uses chlorine for weekly shock treatments
-High levels of copper can lead to green hair and brown or black staining on pool surfaces. Like all other systems, frequent testing of the sanitizer is recommended to ensure the proper levels are present, in this case, the copper level is monitored.

Algaecides

These pool chemicals supply an added layer of protection in the never-ending battle against algae and should be included as part of any chemical maintenance program for outdoor swimming pools.

Quaternary Ammonia
-The most common algicide used in pools.
-Also known as "Quats", this type of algicide is great for maintanence and light algae growth.
-Found in liquid form in varying concentrations, most concentrations of this type of algicide can range from around 5% to 50%
-If overdosed, it can cause foam on top of the pool water, which can increase with agitation, so be sure to follow the instructions on the bottle correctly.

Polyquats
-Used primarily for stubborn or existing algae growth.
-Does not cause foaming.
-More expensive than "quats" but better at killing and preventing algae.
-Usually found in concentrations of 50%-60%.

Metallic
-Found in the form of Copper Sulfate Pentahydrate and Colloidal Silver.
-Although both types are extremely effective against algae, improper dosing or imbalanced water can cause permanent staining on pool surfaces. Use these pool chemicals with caution.
-Used primarily for stubborn or persistent algae growth.

Borates (Sodium Tetraborate, Borax)
Inhibits algae growth by effecting its ability to process carbon dioxide.
Considered to have multiple benefits including reduced sanitizer use, reduced skin and eye irritation, and improved water clarity.
Measurable and considered to be most effective in ranges of 30-50ppm

Bromine Salts (Sodium Bromide)
-Considered to be a "shock enhancer", the use of this chemical during a shock treatment creates hypobromous acid, the acting sanitizer in bromine systems, which is widely recognized for its algae-killing properties.
-One of the most effective pool chemicals for fighting mustard and black algae.
-Should not be used in biguanide based systems, only systems compatible with chlorine and bromine.
-Commonly called Mustard Algae Treatment, Black and Mustard Treatment, Yellow Treat, and others.

Shocks/Oxidizers

One of the more misunderstood pool chemicals, shocks and oxidizers are used to aid sanitizers in the effort to control bacteria and algae growth. They work by destroying organic compounds and sanitizer bi-products (like chloramines and bromamines), which get in the sanitizer's way, inhibiting its ability to perform its #1 job: killing germs and bacteria.

For clear and clean pool water, shock treatments should be added to swimming pools on a weekly to bi-weekly basis, depending on how often the pool is used. Take note that chlorinated shock treatments will raise the Free Chlorine level of the pool water beyond what is deemed "safe" for swimming and the pool should not be entered until FCl levels return to the normal range of 1 to 4ppm.

Sodium Di-Chlor
-A granular form of chlorine dosed at one pound per 10,000 gallons of pool water when used as a shock treatment.
-It is stabilized, meaning it contains cyanuric acid.
-Strong and quick-dissolving chlorine compound with a near neutral pH (6.8).

Calcium-Hypochlorite (Cal-Hypo)
-Found in tablet and granular form, but the granular is primarily used for shock treatment.
-Calcium based chlorine commonly found in strengths of up to 78%.
-Mildly increases Calcium Hardness levels in the pool water, thus it should be avoided if the hardness levels are already high.
-High pH of around 11.8 means it is apt to raise the pH level in the pool when added and should not be added to pools with an already above-range pH over 7.8 to decrease the potential for scale formation on the pool surfaces.
-Should NEVER be added through the pool skimmer, only broadcast or pre-dissolved and then poured around the pool.

Lithium Hypochlorite (Litho Shock)
-Fastest dissolving form of granular chlorine
-High pH of around 10.7
-Low available chlorine percentage with high oxidizing power, meaning it won't raise the chlorine level in the pool as high as other forms of shock treatment can.
-Recommended in doses of 2 pounds per 10,000 gallons of pool water.
-Great oxidizer, but considerably expensive in comparison to other shock treatment options.

Sodium Hypochlorite (Bleach, Liquid Chlorine)
-Liquid form of chlorine ranging in strengths of 6%-12%
-Preferred in higher strengths as oppose to household bleach, which is around a 1-2% solution.
-High pH of near 13.0
-Fastest acting form of chlorinated shock treatment, making it a powerful choice for algae treatment.
-Non-stabilized, and will dissipate rapidly in UV light.
-Bottles have vented caps and can leak if tipped.

Non-Chlorine Oxidizer (Monopersulfate or MPS and Potassium Peroxymonosulfate, a MPS substitute)
-Oxidizes contaminants without the addition of chlorine.
-Reacts quickly to aid in clearing water and leaves the pool usable within 15-20 minutes.
-Primary shock treatment for bromine pools, oxidizing unwanted bromamines and revitalizing bromine's ability to sanitize.
-Commonly used with mineral based systems in both pools and spas.

Supportive Pool Chemicals

Clarifiers
-Help to clear cloudy water by causing suspended particles to coagulate or cling together, making it easier for the filter system to catch them.
-Some clarifiers are enzyme based, "digesting" organic compounds.
-Can be added to a pool on a weekly or "as-needed" basis.

Metal Removers
-Deactivates unwanted levels of Iron, Copper, and other metals in an effort to prevent staining and water discoloration.
-Often used after a significant level of water has been added that contains unwanted metals.
-Can sometimes contain phosphates.

Stain & Scale Inhibitors
-Similar to metal removers in that it controls stains caused by minerals in the water.
-Prevents the formation of scale caused by high Hardness levels in the pool water.
-Often used in weekly maintenance doses to protect equipment and pool surfaces.

Cyanuric Acid (Stabilizer)
-Protects chlorine molecules from dissipating rapidly in the presence of UV light.
-Sometimes referred to as "Sunblock for Chlorine".
-Is only added to pool water "as-needed" and levels of cyanuric acid can be measured and maintained (Suggested range of 30-50ppm).
-Is commonly found built-in to tablet and granular forms of chlorine. (Di-chlor and Tri-chlor)
-Cyanuric acid levels over 100ppm can lead to a condition called "chlorine lock", which interferes with chlorine's sanitizing capabilities and can lead to cloudy water and staining.
-Being an acid, it affects pH and Alkalinity in the pool water. High levels may require the water balance to be adjusted.

Disclaimer

Know-Your-Pool.com provides this information for educational purposes only. All pool chemicals have the potential to be dangerous if improperly used or mishandled. Carefully follow any instructions on product labels regarding use, disposal, and handling procedures, to prevent any personal injury and/or damage to equipment or pool surfaces.

It is the sole responsibility of the pool care provider and/or pool owner to ensure that any and all chemicals are used in accordance with product labeling and instructions.

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