What pool chemicals do I need and how much?

As Pool Service Professionals in Perth, we often get asked by our clients what pool chemicals do they need, and how much? Well…

Pool water chemistry can be the most difficult to understand and often pool owners can get this horribly wrong. Adding the right amount of pool chemicals keeps your water balanced and protects your pool equipment from damage due to high levels of chemical imbalance. Balanced pool water is essential when maintaining a safe and clean environment for the pool to swim in.

No matter how big your pool is, balancing the water is critical.
Sanitising your pool is integral to stop pathogens and algae growth. Using the correct amount of chemicals will balance your pool water’s pH, alkalinity and calcium hardness levels. Each chemical that you add to your pool water has a unique job.

water balance testing

What Chemicals Do I Need?

Putting the right chemicals into your pool balances your water and ensures proper sanitation levels. 


The key to keeping your pool clean is using a suitable sanitiser. Luckily, there are several options to choose from:

    • Sodium Hypochlorite –  Also known as liquid chlorine and probably the most used throughout Australia. It is a relatively weak sanitiser (around 12%) and when added to water splits into two parts – hydrochloric acid and  hypochlorite ions. The pH level in your pool will determine how effective the chlorine performs.
    • Calcium Hypochlorite –  A high strength sanitiser at around 70% you need to either dilute this first or add this directly to the skimmer. Great for use on black spot or mustard algae but it will raise your calcium and pH so beware of staining. 
    • Dichlor(3 in 1) – A fast diluting high strength sanitiser and most commonly used as a shock treatment. Contains isocyanuric acid so will raise your cyanuric (stabiliser) levels and this can soon become out of control if you’re adding it to your pool or spa frequently. This then becomes difficult to dilute out without draining most of your pool or spa.
  • Non Chlorine Shock –  Also known as shock and swim this monopersulfate oxidises the bacteria the same as chlorine. Great for small spas or pools as an alternative to chlorine or when you want to swim in a short time.
  • Salt –  Although not a sanitiser alone,  when used with electrolysis through a salt cell will create chlorine gas at the cell to sanitise your pool. You will need to maintain the salt levels between 2000 – 6000ppm depending on the salt chlorination system you have installed and inline with the manufacturer’s instructions.

Water Balancers

Keeping your pool water balanced is an essential part of pool maintenance. Here are the most common water balancers you can use:

  • Alkalinity increaser – Also known as sodium bicarbonate, alkalinity increaser is one of the first chemicals to consider when balancing your pool water. We recommend adding 453 grams of sodium bicarbonate for every 38,000 litres of pool water to achieve adequate total alkalinity levels. 
  • Alkalinity decreaser – If your alkalinity levels are too high, using alkalinity decreaser, or acid will balance your pool water. Adding acid will also affect your pH.
  • pH increaser (soda ash) – Maintaining the proper pH and alkalinity improves the sanitising ability of the chlorine in your pool. This is a very rarely used chemical as salt systems create soda ash as a bi-product with electrolysis. Most sanitisers will raise your pH  to some degree, except chlorine gas. 
  • pH decreaser – When your pool water’s pH levels are too high you can acid to lower it. Whether that be in dry or liquid form.
  • Calcium hardness increaser – Calcium harness can determine how soft or hard your water feels. The texture of your pool water affects swimming and the overall feel of the water. It is essential to maintain calcium levels in a concrete or plaster pool as the calcium is essential to bind the mortar together. Pool surfaces of this type will fail when the correct levels are not maintained. With a fibreglass pool only the minimum levels would be required150 -450mg/l  to align your saturation index.
  • Cyanuric acid – Essential to maintain sanitiser levels as the UV will degrade or burn it off too quickly especially in the height of summer. The level of cyanuric acid will depend on the system you have but between 20 – 50 mg/l is the Western Australian code of practice.

In addition to sanitisers and water balancers, you may want to consider some of the following specialty chemicals: 

  • Algaecide – Algae is a common problem that faces both residential and commercial pools. Adding an algaecide after balancing your pool prevents algae growth.
  • Phosphate remover – You can use a phosphate remover alongside algaecide to accelerate algae removal. It works by filtering the phosphates in your pool, preventing algae growth. Phosphates are food for algae and can be either brought into the pool from swimmers or from the environment. Keep phosphate levels low. 
  • Pool clarifier – Pool clarifiers work by coagulating contaminants in your water and bridging them to the surface so they can be filtered out by the pool system.

Stain and scale prevention – Preventing organic stains keeps your pool and equipment looking tip top.. Stain and scale prevention chemicals add to the pleasing aesthetic of your water while contributing to algae prevention.  

pool pump startup

What Is the Ideal Chemical Balance for a Pool Start-Up?

With so many chemicals to add to your pool, knowing what numbers to aim for is essential. Typically, you want to aim for your pool to reach these levels for each chemical solution:

  • pH: 7.2-7.8
  • Alkalinity: 80-120 mg/l
  • Calcium hardness: 150-450 mg/l
  • Cyanuric acid: 20-50 mg/l
  • Chlorine: 1-3 mg/l Dependent on the use of isocyanuric acid and water temperature

When your pool test kit reads back these numbers, your water is properly balanced! 

What Is Proper Water Balance?

The water in your pool may not seem like it needs constant maintenance, but balancing your pool water has a significant effect on your pool’s cleanliness and the softness of your water. 

Chemical levels contribute to the balancing process of your pool water: pH, TDS, alkalinity, chlorine, total chlorine, isocyanuric acid and calcium hardness

pH Levels

You will know that your pool water is balanced correctly when the pH levels read between 7.2 and 7.8.

The pH level of your pool water can be affected by rain, debris, or pretty much anything that enters your pool. A low pH level indicates acidic water, whereas a high pH means that your water is basic. 

Keeping pH increasers and decreasers handy when measuring your pool’s pH level makes it easier to keep your water clean enough to swim in. 

Alkalinity Levels

The alkalinity in your water keeps your pH levels in check. However, alkalinity levels fluctuate quickly, so it is a good idea to keep alkalinity increasers handy. 

When balancing your pool water, you should aim for an alkalinity level of 60 – 180 mg/l. 

Calcium Hardness

A proper calcium level in your pool water protects the structural integrity of the pool walls and floor. Too little calcium could result in deterioration of the pool surface over time. However, too much calcium can cause other issues as well and can plate out on walls, floors and equipment if the pH is not maintained.

Aiming for a calcium hardness level between 150 mg/l and 450 mg/l  will keep your pool balanced.

adding chemicals to your pool

What Order Should You Put in the Pool Chemicals?

Now you know what each chemical does and how much of it you should add to your pool water, but does it matter what order you put the chemicals? The answer is yes. When balancing your pool water, follow these steps to ensure your chemicals are added in the correct order:

  1. Total alkalinity – Alkalinity stabilises the pool water and makes it easier to adjust pH levels. Adding total alkalinity paves the way for the rest of the chemicals. 
  2. pH increasers or decreasers – Aiming for pH levels between 7.2 and 7.8 encourages the chlorine in your water to work more effectively while keeping the water comfortable to swim in. 
  3. Calcium hardness – Calcium hardness affects how the pool water feels when you swim in it. Adjusting calcium hardness is easier when your pool water is already balanced. 
  4. Chlorine or sanitiser – Your pool sanitiser works best once your pool water is balanced and has the correct amount of calcium hardness. 
  5. Cyanuric acid – Before adding the final chemical, test your pool water. A majority of sanitisers have cyanuric acid in them already. Cyanuric acid helps the chlorine in your pool work better by protecting it from the sun’s UV rays. 

Pool Chemical Professionals in Perth, Australia

Balancing your pool requires the right amount of chemicals and depends on accurate measurements. 

As pool experts, 1 Pool Care recommends that you shock your pool at least once a week. Some events, such as pool parties or rainstorms, require more frequent pool shocking. 

Maintaining your residential or commercial pools requires time and attention. When your busy schedule doesn’t give you the opportunity for proper pool care, let the 1Pool Care team take care of it for you. 

Our experts know what measurements to aim for and what chemicals to use to keep your pool clean and feeling great. 

When you need pool chemical and water balancing assistance, call 1 Pool Care on 0456757575. We’ll take care of your pool, so all you have to do is worry about enjoying it!

Learn more about WBA members 1 pool Care in our Members Directory here



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