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Advanced Above Ground Pool Chemistry

Updated: Dec 22, 2022

First time visitors may wish to start here to get familiar with the basics of above ground pool chemistry.

This guide will introduce above ground pool owners to the more advanced side of above ground pool chemistry. This guide focuses solely on vinyl above ground pools in the Canadian climate. Always refer to guides for pool types/climates appropriate to your situation.

We will dive deep into borates, phosphates, metals, cleaners, clarifiers, and other supplements to your basic weekly maintenance and water balancing routines. Click here to view how basic weekly maintenance works for above ground pools in Canada.

Advanced Chemistry & Situational Chemicals

Total Dissolved Solids

Total Dissolved Solids (TDS) is the measure of dissolved substances in your pool's water. TDS can be increased by pool chemicals, metals, organic matter, oils, and more. Although TDS is not something that you check with your weekly test strips, your pool store will be able to test for you. High TDS can lead to clarity issues, reduced chemical effectiveness, scaling, and more. High TDS can only be decreased by dilution. If you experienced prolonged clarity issues, checking TDS can help in the elimination process. Salt water pools will have a high TDS by nature due to dissolved salt. As the salt is very soluble, the high reading of TDS caused by salt is not an issue.

  • 2000ppm or lower on non-salt pools


Copper is the most common of all metals to be present in pool water. Copper can be introduced to the pool in several ways, including from the source of the water (e.g. a well with a high copper content in the water), from damaged heat exchangers in your heater leaching into the pool, or from overuse of algaecides or mineral systems. Copper tends to manifest as green stains on the liner, or by bleaching the hair of bathers green. Very small copper readings (0.5ppm or less) may be present due to algaecide, but if any signs of copper issues manifest themselves, consult your local pool store for the correct metal remover chemical protocol.

  • 0ppm


Unlike copper, iron and manganese will only come from the water supply. Older inground pool heaters used to have iron headers, which could be a source of iron, but modern above ground heaters do not. Iron and manganese typically manifest as red or dark black staining, and will be treated with a metal remover chemical protocol just like copper.

  • 0ppm


Measuring for phosphates is a fairly recent development for above ground pools. Marketed by pool supply companies as being "the food for algae", phosphates are often misunderstood by pool owners. A realistic assessment of whether or not to try to balance phosphates boils down to this. All organic matter, swimmers, and even chemicals can and will leach phosphates into your pool. Balancing phosphates requires a constant battle to lower levels by adding phosphate reducers. This being said, if you do not attempt to eliminate the phosphates in your pool, what will happen? As long as you balance the big 5 (listed above) nothing will happen. Although phosphate remover tries to eliminate phosphates in order to kill the food for the algae, maintaining proper levels of chlorine and using a weekly algaecide will create a hostile environment that algae cannot grow in. This makes the futile fight with phosphates utterly pointless. Your energy is better spent on balancing chlorine, pH, alkalinity, stabilizer, and calcium hardness for proven results.


For the pool chemistry aficionado, borates may attract the keen eye. Borates are often seen as a great supplement to basic pool chemistry. Acting as a pH buffer, algaestat, clarifying agent, and water conditioner for softer feeling water, borates are often considered to be more of a luxury or optional chemical. Not required by any means, although they can augment the quality of your pool's water. Borate products such as Bioguard Optimizer Plus are the most common. For any customers looking to maximize their swimming experience, Optimizer Plus can be a great addition, but for pool owners that value simplicity and ease of use without having to test for and consider another chemical, sticking with the basics of pool chemistry 101 is fine. Testing at home for borates requires purchase of specialized test strips. Although borates are often marketed as a once in a season addition, borates levels have to be tested for regularly and often require multiple doses a year due to backwashing, splash over, etc. Although they can definitely allow you to get more out of your pool, they are not the fix all propagated by some.

  • 35ppm (if applicable)


Flocculants are typically used to help resolve clarity issues in pools. Flocculants cause all the small particles floating in suspension to bind together and sink to the bottom of the pool. After a treatment of floc, a pool will often go from cloudy with limited visibility to a clear pool with lots of debris at the bottom. The most important part of a floc treatment is to turn the pump off prior to adding floc. If the pump is on and the floc gets into the filter, the filter media can be ruined and have to be replaced. If added correctly, the pump will be turned off, floc added, and then the pool can be vacuumed to waste 24hr after adding the floc. When extremely green pools need to be remedied, the "shock and flock" method is typically employed. Please note that flocculants cannot be used with cartridge filters.


Another supplement to basic pool water chemistry is the clarifier. Similar to a flocculant, clarifiers cause small particles to clump up in order to be cleaned. However, unlike flocculants which cause debris to settle to the bottom of the pool and require the pump to be off, clarifiers cause clumped debris to float to the surface which can then be cleaned by your pool's filtration system while the pump stays on. Clarifiers are typically used as needed for that extra bit of shine. Refer to your filter's manufacturer to check whether or not clarifiers can be used with your filtration system.

Stain and Scale Remover

For any pool owners that primarily use well water to fill the pool, stain and scale removers may need to be used occasionally to deal with any tough stains. Stain and scale removers are primarily used for mineral and metal staining, tied to copper, iron, and manganese. This can also be used on scaling caused by high pH or calcium hardness, although this is far less common an issue with vinyl above ground pools. The stain and scale remover works by chemically breaking up the stain allowing it to be brushed up to the pool's surface, to then be caught by the pool's filter. Ensuring a proper backwash and rinse cycle is performed after using stain and scale remover for large stains will keep your filter clean as well.


For most pool owners, algaecides will be an essential component of their weekly maintenance routines. Salt water pool owners can skip the algaecide step as long as they properly maintain their pH and stabilizer. Algaecides work in theory by either killing (algaecide) or preventing (algaestat) the small algae particles before they can bloom and lead to green pool water, or physical green algae deposits in your pool. Algaecides are typically comprised of either a polyquat or copper sulfate base, at varying percentages. Although there is some debate in the industry regarding polyquats vs metal based algaecides, in the context of vinyl above ground pools used in the limited Canadian summers at less than tropical temperatures, either will suffice when used properly based on the types of algae we are trying to prevent. Algaecide should be added with the weekly maintenance routine, in doses conforming to manufacturer specs. Ensuring you do not dose too high is extremely important, and overdosing the pool with either a polyquat or copper based algaecide can have ill effects on the pool, such as foaming, high copper readings, and causing dyed hair to turn green.

Filter Cleaners

Cleaning the filter media of your pool is required no matter what style of filter you have. Over time, oils and other grease particulates from sunscreen, bather's bodies, or organic matter will build up inside the filter. Even through routine backwashing (sand filter) and external filter cleanings (cartridge) will clean the filter of any debris or built up gunk, it will not remove fine oils and grease. Using a filter cleaner will purge the filter of remaining oils to really get the filter as clean as possible. Filter manufacturers typically recommend a chemical filter cleaning once per season. Cartridge filters are typically cleaned once per month by removing the cartridge from the filter, spraying the cartridge down with a garden hose, making sure to get all debris between the pleats, and the reinstalling the filter. To clean with a chemical filter cleaner, fill a clean plastic container full of water, submerging the cartridge. Add the chemical package, stir, and let sit for manufacturer recommended time (typically 12-24hrs). Remove and rinse the cartridge, then reinstall to filter. Cleaning a sand filter with filter cleaner is also relatively easy. Start by backwashing and rinsing your sand filter for 1 minute on backwash, and 30 seconds on rinse. Bring the filter dial back to filtration and leave pump off. Apply the filter cleaner package into the pump basket, and turn pump on for 5 seconds, then turn off. This will push the filter cleaner granules from the pump basket up into the sand filter. Let the filter sit for for manufacturer recommended timeframe (typically 1 hour), and then backwash and rinse the filter again. You will notice the the discharge from the backwash will contain lots of suds and discoloured water, which shows the cleaner has worked. Return to filter position and operate as normal.

Salt Cell Cleaners

As the name suggests, salt cell cleaners are used to clean the salt cell from any calcium or scaling build up that occurs on the metal fins and sensors inside the salt cell. This build up will prevent the cell from generating chlorine properly, and can damage the cell leading to early failure. Most manufacturers recommend cleaning the cell 1-2 times per year. For most pool owners, this would mean during the middle and end of your pool season. Although most generators will alert you when the cell needs to be cleaned, further preventative maintenance in the form of cell cleaning will extend the life of your cell. Salt cell cleaners are acids that will burn off the scaling within the cell. Typically, one end of the salt cell is plugged off using an expandable winter plug, and the acid is poured into the top half while the cell stands upright. Placing the cell within a plastic container such as a garbage bin is recommended incase the cell tips over and the acid spills. Leave the cell to sit for the recommended length of time suggested by manufacturer (this varies based on the strength of the acid), and poured out the cell disposing of the acid in the way recommended by the manufacturer.

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