Comprehensive Guide to Pool Chemicals
To have your pool water balanced, you need to maintain appropriate levels of pH, chlorine, total alkalinity, calcium hardness & stabiliser. There is a minimum, maximum and ideal level for each chemical, so ideal is the target to strive for. If your pool is a traditional salt pool or magnesium pool, these levels also need to be monitored and corrected when needed. Correct pH of the water is needed firstly. The other chemicals can’t do their job properly if pH is too high or too low.
Balance pH Levels
The first step is adjusting the pH of the water, so it’s within range.
pH is an abbreviation for “potential hydrogen” and is a measure of the acidity of the water. The pH scale ranges from 0 to 14, with 7 being neutral. Anything above 7 is alkaline and everything below is acidic.
For swimming pools, the ideal range is between 7.2 to 7.8. The ideal pH for concrete or vinyl liner pools is 7.4. The optimal for fibreglass pools is 7.2.
Increase pH Levels
Soda Ash
- Sodium carbonate, known as soda ash is used to raise the pH of your pool water.
- Soda ash helps prevent corrosion, keeps the water stable, but also raises the alkalinity of the water.
Aeration
- Aeration is a natural method to increase the pH of water without increasing Total Alkalinity (TA).
- Introduce air into the water to disturb surface tension by splashing, running fountains, pointing pool outlets upward, or adding compressed air.
Decrease pH Levels
Muriatic Acid, Hydrochloric Acid or Dry Acid
- Muriatic or hydrochloric acid is a liquid product and care must be taken when handling.
Dry acid also known as pH Down or pH Minus is made from sodium bisulphate.” to “Dry acid also known as pH Down, pH Decreaser or pH Minus and is made from sodium bisulphate.
- It’s safer and less corrosive to use than muriatic or hydrochloric acid.
Chlorine & Shock Treatment
Chlorine is the most commonly used sanitiser in swimming pools, because it’s effective in killing bacteria and preventing algae growth.
There are two types of chlorine in your pool: free chlorine and combined chlorine:
Total Chlorine
The total chlorine amount in a pool is the total of both free chlorine and combined chlorine in a body of water.
Free Chlorine
The amount of chlorine available to do the work of disinfecting and sanitising.
Combined Chlorine
Combined chlorine is chlorine that has reacted with organic matter and is now no longer effective. To determine combined chlorine levels, subtract free chlorine levels from total chlorine levels. As example, if total chlorine was 4 ppm and free chorine was 3 ppm, the combined chlorine level would be 1 ppm.
Increase Free Chlorine Levels
Manually increasing chlorine is either done by adding granular chlorine or liquid chlorine.
Liquid chlorine is a better option, as it doesn’t leave any residue on the floor of the pool.
Adding large amounts of granular chlorine can make the water cloudy, particularly if it is not fully dissolved before adding to the pool.
Decrease Free Chlorine Levels
Exposure to UV will reduce chlorine levels gradually over time.
Chlorine levels can be brought down quickly by using sodium thiosulphate to neutralise chlorine and lower its concentration.
Decrease Combined Chlorine Levels
Non-chlorine shock, also known as potassium monopersulphate, is a widely used oxidising agent that helps to eliminate organic contaminants without increasing chlorine levels.
Potassium monopersulphate does not produce chlorine odours, or contribute to chlorine build-up, which makes it ideal for regular use.
Total Alkalinity (TA)
Total alkalinity is the sum of all alkaline substances in your water.
In swimming pool water, the total alkalinity (TA) should be between 80 to 120 parts per million.
Total alkalinity within the ideal range stabilises the pH level of your pool and will prevent rapid pH changes.
Increase Total Alkalinity Levels
There are various products available to increase alkalinity such as Buffer, Alkalinity Increaser or Alkalinity Up.
Decrease Total Alkalinity Levels
Hydrochloric Acid, Muriatic Acid, or Dry Acid is used to lower alkalinity levels in your pool.
Dry acid also known as pH Down or pH Minus is made from sodium bisulphate.
It’s safer to use and less corrosive than hydrochloric or muriatic acid, but still must be handled with care.
Total Hardness
Total hardness is the total amount of dissolved minerals, which is calcium and magnesium ions in the pool water.
For a swimming pool it’s the calcium harness we want to measure and if a mineral pool we want to separate the calcium from magnesium levels.
Calcium hardness measures the amount of dissolved calcium in your pool water, the recommended range is between 80 to 500 parts per million.
Calcium hardness can increase through the regular use of pool chemicals (ie granular chlorine contains calcium hypochlorite).
When calcium hardness is too low, the water can become corrosive. This can damage your pool surfaces, equipment, pipe fittings and pump connections. Your pool walls and floor can also stain.
If calcium hardness is too high, scaling can form on all of your pool surfaces. The water can become cloudy and swimmers may complain of eye irritations.
Increase Calcium Hardness Levels
High calcium levels can lead to calcium deposits (scaling) forming on pool surfaces, inside plumbing pipes or on equipment.
High calcium can also make your pool water cloudy.
Low levels of calcium has the water more aggressive, which can cause etching on pool surfaces and damaging equipment.
To increase calcium hardness, calcium chloride is added to the water.
Decrease Calcium Hardness Levels
Lowering calcium hardness is more difficult and can be done using these steps:
- Drain some of your pool water and replace it with softer water;
- Use a flocculent to attract excess levels of calcium, causing it to clump and collect at the bottom of your pool (which will then need to be vacuumed to waste).
- Use a calcium reducer or calcium hardness decreaser product. Refer to the manufacturer’s instructions for dosage quantities and procedures for adding to your pool.
Stabiliser
Stabiliser (CYA) acts like sunscreen for chlorine and is needed in outdoor pools to maximise chlorine’s effectiveness.
Stabiliser not only extends the life of chlorine, but also reduces chlorine consumption.
On a hot summer day due to UV exposure, your pool could lose up to 80% of its chlorine within 2 hours.
With the right levels of stabiliser, your pool will only lose about 20% over the same time period.
Free chlorine should be 7.5% of stabiliser levels, which is why a chorine target of 3ppm equals a stabiliser level of 40ppm.
Increase Stabilser Levels
Cyanuric acid is a chemical compound that is used to increase stabiliser levels in swimming pools.
Decrease Stabiliser Levels
The only way to reduce stabiliser levels is through dilution, which means to drain or part-drain your pool and replace with fresh water.
- Calculate the amount to be drained by using current stabiliser level and the target stabiliser level.
- Use a submersible pump to drain the pool by the required amount.
- Refill with fresh water & retest all chemicals after running the filter for 2-3 days.
Algae Prevention & Algaecide
Adding algaecide to your pool will enhance and prolong the effectiveness of the chlorine you’re using for sanitising your pool and be a valuable back-up for helping prevent future algae growth.
Normally algaecide is best used as a preventive for algae, although there are some copper-based products that are also effective in killing algae. Use copper-based algaecide in moderation, as excessive metals in your pool can cause staining.
Algaecide is a good winteriser product to add to your pool, because during this time filtering times are halved and for some people, they don’t maintain chlorine as regularly as they should be.
Salt
Salt water chlorinators have a salt cell plumbed into the return lines.
When the filtration system is running, salt that is in the water passes through the cell and an electrolysis process converts the sodium chloride (salt) into chlorine.
As the chlorine becomes used, it turns back into sodium chloride, so it a 100% recyclable process.
Increase Salt Levels
Calcium chloride is used to increase salt levels in swimming pools.
Decrease Salt Levels
The only way to reduce salt levels is through dilution, which means to drain or part-drain your pool and replace with fresh water.
- Calculate the amount to be drained by using the current salt level and target salt level.
- Use a submersible pump to drain the pool by the required amount.
- Refill with fresh water & retest all chemicals after running the filter for 2-3 days.
Minerals
Mineral pools use exactly the same chlorinators as salt pools, so they also have the salt cell plumbed into the return lines.
When water passes through the cell, the mineral salts are converted into chlorine through electrolysis.
As chlorine is exhausted, it reverts back to mineral salts, the same 100% recyclable process as with salt water pools.
Increase Mineral Levels
Minerals are used to increase mineral salt levels in swimming pools.
Decrease Mineral Levels
The only way to reduce mineral salt levels is through draiingn or part-draining your pool and replacing with fresh water.
- Calculate the amount to be drained by using the current and target mineral salt levels.
- Use a submersible pump to part-drain the pool as required.
Use fresh water to refill the pool & retest all chemicals after running the filter for 2-3 days.
Phosphate Remover
Phosphate remover is a specialist product made by several manufacturers and will reduce the level of phosphates in your pool.
Phosphates are food for algae, so by removing phosphates it can prevent algae from growing in your pool.
Metal Reducer
Metal chelating agents or sequestrants are used to manage and reduce the concentration of metals in pool water.
The first step is adjusting the pH of the water, so it’s within range.
pH is an abbreviation for “potential hydrogen” and is a measure of the acidity of the water. The pH scale ranges from 0 to 14, with 7 being neutral. Anything above 7 is alkaline and everything below is acidic.
For swimming pools, the ideal range is between 7.2 to 7.8. The ideal pH for concrete or vinyl liner pools is 7.4. The optimal for fibreglass pools is 7.2.
Increase pH Levels
Soda Ash
- Sodium carbonate, known as soda ash is used to raise the pH of your pool water.
- Soda ash helps prevent corrosion, keeps the water stable, but also raises the alkalinity of the water.
Aeration
- Aeration is a natural method to increase the pH of water without increasing Total Alkalinity (TA).
- Introduce air into the water to disturb surface tension by splashing, running fountains, pointing pool outlets upward, or adding compressed air.
Decrease pH Levels
Muriatic Acid, Hydrochloric Acid or Dry Acid
- Muriatic or hydrochloric acid is a liquid product and care must be taken when handling.
Dry acid also known as pH Down or pH Minus is made from sodium bisulphate.” to “Dry acid also known as pH Down, pH Decreaser or pH Minus and is made from sodium bisulphate.
- It’s safer and less corrosive to use than muriatic or hydrochloric acid.
Chlorine is the most commonly used sanitiser in swimming pools, because it’s effective in killing bacteria and preventing algae growth.
There are two types of chlorine in your pool: free chlorine and combined chlorine:
Total Chlorine
The total chlorine amount in a pool is the total of both free chlorine and combined chlorine in a body of water.
Free Chlorine
The amount of chlorine available to do the work of disinfecting and sanitising.
Combined Chlorine
Combined chlorine is chlorine that has reacted with organic matter and is now no longer effective. To determine combined chlorine levels, subtract free chlorine levels from total chlorine levels. As example, if total chlorine was 4 ppm and free chorine was 3 ppm, the combined chlorine level would be 1 ppm.
Increase Free Chlorine Levels
Manually increasing chlorine is either done by adding granular chlorine or liquid chlorine.
Liquid chlorine is a better option, as it doesn’t leave any residue on the floor of the pool.
Adding large amounts of granular chlorine can make the water cloudy, particularly if it is not fully dissolved before adding to the pool.
Decrease Free Chlorine Levels
Exposure to UV will reduce chlorine levels gradually over time.
Chlorine levels can be brought down quickly by using sodium thiosulphate to neutralise chlorine and lower its concentration.
Decrease Combined Chlorine Levels
Non-chlorine shock, also known as potassium monopersulphate, is a widely used oxidising agent that helps to eliminate organic contaminants without increasing chlorine levels.
Potassium monopersulphate does not produce chlorine odours, or contribute to chlorine build-up, which makes it ideal for regular use.
Total alkalinity is the sum of all alkaline substances in your water.
In swimming pool water, the total alkalinity (TA) should be between 80 to 120 parts per million.
Total alkalinity within the ideal range stabilises the pH level of your pool and will prevent rapid pH changes.
Increase Total Alkalinity Levels
There are various products available to increase alkalinity such as Buffer, Alkalinity Increaser or Alkalinity Up.
Decrease Total Alkalinity Levels
Hydrochloric Acid, Muriatic Acid, or Dry Acid is used to lower alkalinity levels in your pool.
Dry acid also known as pH Down or pH Minus is made from sodium bisulphate.
It’s safer to use and less corrosive than hydrochloric or muriatic acid, but still must be handled with care.
Total hardness is the total amount of dissolved minerals, which is calcium and magnesium ions in the pool water.
For a swimming pool it’s the calcium harness we want to measure and if a mineral pool we want to separate the calcium from magnesium levels.
Calcium hardness measures the amount of dissolved calcium in your pool water, the recommended range is between 80 to 500 parts per million.
Calcium hardness can increase through the regular use of pool chemicals (ie granular chlorine contains calcium hypochlorite).
When calcium hardness is too low, the water can become corrosive. This can damage your pool surfaces, equipment, pipe fittings and pump connections. Your pool walls and floor can also stain.
If calcium hardness is too high, scaling can form on all of your pool surfaces. The water can become cloudy and swimmers may complain of eye irritations.
Increase Calcium Hardness Levels
High calcium levels can lead to calcium deposits (scaling) forming on pool surfaces, inside plumbing pipes or on equipment.
High calcium can also make your pool water cloudy.
Low levels of calcium has the water more aggressive, which can cause etching on pool surfaces and damaging equipment.
To increase calcium hardness, calcium chloride is added to the water.
Decrease Calcium Hardness Levels
Lowering calcium hardness is more difficult and can be done using these steps:
- Drain some of your pool water and replace it with softer water;
- Use a flocculent to attract excess levels of calcium, causing it to clump and collect at the bottom of your pool (which will then need to be vacuumed to waste).
- Use a calcium reducer or calcium hardness decreaser product. Refer to the manufacturer’s instructions for dosage quantities and procedures for adding to your pool.
Stabiliser (CYA) acts like sunscreen for chlorine and is needed in outdoor pools to maximise chlorine’s effectiveness.
Stabiliser not only extends the life of chlorine, but also reduces chlorine consumption.
On a hot summer day due to UV exposure, your pool could lose up to 80% of its chlorine within 2 hours.
With the right levels of stabiliser, your pool will only lose about 20% over the same time period.
Free chlorine should be 7.5% of stabiliser levels, which is why a chorine target of 3ppm equals a stabiliser level of 40ppm.
Increase Stabilser Levels
Cyanuric acid is a chemical compound that is used to increase stabiliser levels in swimming pools.
Decrease Stabiliser Levels
The only way to reduce stabiliser levels is through dilution, which means to drain or part-drain your pool and replace with fresh water.
- Calculate the amount to be drained by using current stabiliser level and the target stabiliser level.
- Use a submersible pump to drain the pool by the required amount.
- Refill with fresh water & retest all chemicals after running the filter for 2-3 days.
Adding algaecide to your pool will enhance and prolong the effectiveness of the chlorine you’re using for sanitising your pool and be a valuable back-up for helping prevent future algae growth.
Normally algaecide is best used as a preventive for algae, although there are some copper-based products that are also effective in killing algae. Use copper-based algaecide in moderation, as excessive metals in your pool can cause staining.
Algaecide is a good winteriser product to add to your pool, because during this time filtering times are halved and for some people, they don’t maintain chlorine as regularly as they should be.
Salt water chlorinators have a salt cell plumbed into the return lines.
When the filtration system is running, salt that is in the water passes through the cell and an electrolysis process converts the sodium chloride (salt) into chlorine.
As the chlorine becomes used, it turns back into sodium chloride, so it a 100% recyclable process.
Increase Salt Levels
Calcium chloride is used to increase salt levels in swimming pools.
Decrease Salt Levels
The only way to reduce salt levels is through dilution, which means to drain or part-drain your pool and replace with fresh water.
- Calculate the amount to be drained by using the current salt level and target salt level.
- Use a submersible pump to drain the pool by the required amount.
- Refill with fresh water & retest all chemicals after running the filter for 2-3 days.
Mineral pools use exactly the same chlorinators as salt pools, so they also have the salt cell plumbed into the return lines.
When water passes through the cell, the mineral salts are converted into chlorine through electrolysis.
As chlorine is exhausted, it reverts back to mineral salts, the same 100% recyclable process as with salt water pools.
Increase Mineral Levels
Minerals are used to increase mineral salt levels in swimming pools.
Decrease Mineral Levels
The only way to reduce mineral salt levels is through draiingn or part-draining your pool and replacing with fresh water.
- Calculate the amount to be drained by using the current and target mineral salt levels.
- Use a submersible pump to part-drain the pool as required.
Use fresh water to refill the pool & retest all chemicals after running the filter for 2-3 days.
Phosphate remover is a specialist product made by several manufacturers and will reduce the level of phosphates in your pool.
Phosphates are food for algae, so by removing phosphates it can prevent algae from growing in your pool.
Metal chelating agents or sequestrants are used to manage and reduce the concentration of metals in pool water.
Introducing Effective Solutions
Simplify your pool maintenance routine with POOLWATER-PRO. Our software turns test-strips into accurate digital readings, right from your phone. Get instant alerts to know if your pool is safe to swim, plus any chemicals needed.
Introducing Effective Solutions
Simplify your pool maintenance routine with POOLWATER-PRO. Our software turns test-strips into accurate digital readings, right from your phone. Get instant alerts to know if your pool is safe to swim, plus any chemicals needed.
Your Path to Clarity
Watch this quick explainer video to see the platform’s features and how it can make pool care hassle-free.
Watch this quick explainer video to see the platform’s features and how it can make pool care hassle-free.
