1 - Essential Chemicals

There is one and only one chemical that stops the pool from going green, and that’s Chlorine. It's the most commonly used element to eliminate bacteria globally and is also odourless and non-irritable.

The smell and stinging comes from what is known as Dead Chlorine. This substance forms when chlorine interacts with bacteria. It usually takes months to build up, but if enough does, it will stop the regular chlorine from killing bacteria all while causing that well known smell. You can get rid of it by:

• Shocking the pool with free chlorine (10x the level of dead chlorine)
• Adding an oxidiser (known as non-chlorine shock).

Maintaining the pH level is also crucial for chlorine to function effectively. Chlorine has a high pH level of 13.0, causing it to quickly lose effectiveness when it enters the pool. To balance the pH, Hydrochloric Acid with a low pH of 1.0 is used.

• At a pH of 7.2, Chlorine will be 62.5% effective,
• At a pH of 8.8, Chlorine will be 9% effective.

2 - Long Term Chemicals

Long-term chemicals are extremely helpful in saving you time and additional costs. For example, the pH is quite unpredictable. It may:

• Increase quickly from the addition of another chemical like chlorine,
• Decrease dramatically from a period of heavy rain.

Having your pH too high, will diminish the effectiveness of your chlorine. Having it too low, will create a very uncomfortable swimming environment. There is a solution to this problem and it’s in your kitchen. In the pool industry, "alkalinity" is a substance, and "alkaline" describes the pH level. Adding this chemical that is also known as Baking Soda will dramatically slow down how quickly your pH can fluctuate. You only need it ever 1-3 months. Adding it will also protect the pool equipment from corrosion.

It cannot however protect the pool from the sun. The sun is your pools biggest enemy, it attacks your most important chemical, chlorine. On a normal day in Australia, you will lose 75% of all chlorine within two hours of exposure to UV rays and it will all be gone by the fourth hour. That’s where Stabiliser (Cyanuric Acid), comes in. This chemical binds to the chlorine molecule and allows the chlorine to last eight times longer. 

The main chemical for protecting equipment and the surface is known as Calcium (Calcium Hardness). If the water is too soft (low calcium), your equipment and plumbing work will corrode. Sadly, you will only notice this before it’s too late.

A lack of Calcium will also cause the water to try and balance it for you. This sounds great until you notice it’s pulling it directly from the pool’s concrete base. This will appear as white staining that protrudes into the water. It's extremely difficult to scrub off and in severe cases, requires the pool to be drained and acid washed, which is very expensive/time consuming.

 

3 - Specialty Chemicals

In some areas of Australia with dense tree populations, there is often a high occurrence of algae growth in pools. This is due to the Phosphates that are regularly dropped into the pool by the trees. Phosphates are found in all living cells and usually enter the pool through leaves, debris, animals, and even urine. Algae primarily feed on Phosphates, which puts pools at risk of growth if phosphate levels are too high. While normal chemicals may not solve this issue, using a Phosphate remover such as Starver can prevent algae growth under the right conditions.

Another option for pool sanitisation besides Chlorine is Copper, which has been used in medicine worldwide for centuries. Copper eliminates bacteria and harmful pathogens. Ionisers are one type of sanitation system that produces Copper (90%) and Silver (10%) to prevent algae growth in pools, but they cannot treat an already green pool. Copper algaecides can also be used to break down algae cells, and can be used alone or in combination with chlorine. Using only Copper results in smoother water with no chlorine taste or odour, low operating costs, but may potentially cause surface stains, require difficult maintenance, and will be far slower at killing bacteria.

To achieve some of the benefits mentioned earlier without the drawbacks, minerals such as Magnesium, Potassium, and Boron can be added to the pool water. These elements make the water feel smooth, silky, and less irritating to people with skin conditions. Adding them will increase the water's total hardness and can be converted into chlorine gas through a salt cell.

Magnesium gives the water a silky feel and helps in attacking algae cells, Potassium is a natural moisturiser, and Borax softens the water hardness to balance it out. Chemical suppliers usually use a combination of salt (75%) and magnesium (25%) to provide the desired effects. However, all brands are significantly different and will vary from bag to bag. 

 

4 - Other Pool Needs 

If your pool is slightly cloudy and has turned green, using clarifier can help the filter collect the particles more effectively. After that, shocking the pool with Chlorine is enough. However, if the pool is very green or brown and the water is opaque, adding flocculant is necessary. Flocculant is a chemical that binds sediment together, and after a few hours to a day, the debris will settle to the bottom of the pool, allowing for manual vacuuming to the sewer. Additionally, the pool will still require a Chlorine shock.

Different types of pool surfaces have varying requirements for certain chemicals. For instance, vinyl/fibreglass pools need less calcium, while copper can cause staining on surfaces such as vinyl, fibreglass, and quartzon/marblesheen. Concrete foundations have several surfaces, including marblesheen, pebblecrete, beadcrete, painted, quartz, and tiled, and require 200-400ppm of calcium to prevent surface damage. In contrast, pools with elevated or fine bedding foundations, such as fibreglass, submerged vinyl, and elevated vinyl, only need calcium to protect equipment from corrosion, and levels as low as 75ppm can suffice.

Maintaining a spa is cheaper and requires fewer chemicals compared to a pool. Bromine is used instead of chlorine as it is more stable in heated water. Mixing chlorine and bromine can create a carcinogenic reaction. Calcium is not needed for spas as they rarely have a concrete foundation. Different sanitisation systems are available, and the surface of the pool determines the level of certain chemicals needed. Concrete foundations require 200-400ppm of calcium, while other types of foundations only need calcium to protect equipment from corrosion.

 

5 - Tips, Tricks & Myths

Chemicals required for maintaining a pool can be expensive in the long run. Weekly to monthly Chlorine/Salt and Acid, monthly to quarterly long-term chemicals, and specialty chemicals are needed depending on various pool factors, totalling an estimated annual cost of $1,730 for an average 50,000L pool in NSW.

Some cost saving tips include:

• Maintain the pool yourself instead of hiring a pool cleaner, there is usually a significant markup in costs for all chemicals as well as labour,
• Use chlorine over algaecides as it’s much cheaper to buy and a lot more effective at killing algae quickly, in most pools there is no need for algaecide,
• Invest in a solar cover to prevent chemical/water evaporation, this piece of equipment will reduce chemical costs by 33% for the foreseeable future.

You can also save money if you:

• Avoid letting the pool turn green to prevent the need for recovery chemicals, you can do this by regularly testing the water (free and highly accurate at most pool shops),
• Avoid purchasing the initially cheaper chlorine doser as salt costs half as much on average as compared with chlorine, over the lifespan of the saltwater chlorinator, you could save up to $3,500,
• Do not buy chlorine from petrol stations, you may be tempted by the larger amount at a cheaper price, however they often leave chlorine sitting in the sun which diminishes its potency.

General chemistry maintenance tips include:

• Testing your pool water at least once a fortnight using a reliable testing kit,
• Keeping your pH levels between 7.2 and 7.6 to ensure maximum effectiveness of your chlorine,
• Always add chemicals to the water, never the other way around,
• Keep your pool filter clean (backwash/hose down every month),
• Don’t mix chlorine and acid together, as this will create a poisonous gas.

Two types of pool chemical retailers exist:

• Professional Pool Stores
• Poolwerx
• Swimart
• Clark Rubber
• Local Stores
• Online Stores

• Non-Specialised Stores
• Bunnings
• Mitre 10
• Coles
• Woolworths
• Other Retailers

For those with serious pool problems and no experience, it's best to consult a professional store with knowledgeable staff, though their products are more expensive. Supermarkets and wholesalers like Coles, Woolworths & Bunnings may offer cheaper products, but their chemicals are usually less potent and can result in a number of problems if used incorrectly.