What chemicals for what purpose?

What chemicals for what purpose?

Does it feel like you need to have a PhD in chemistry to understand how to care for and maintain the water balance in your pool or spa? Chemically balanced water is the key to a clean pool or spa. Improperly balanced water can cause algae and bacteria growth and cause waterlines to form. There are three categories of chemicals we recommend you using: sanitisers, water balancers and speciality. To help make it all a bit easier to understand, here’s our guide to what chemicals you need and how to use them.


Arguably the most important of pool chemicals, sanitisers are the chemicals you use to keep water free of bacteria, algae, viruses and other micro-organisms that can grow in untreated pool or spa water. We stock a few sanitisers to choose from.

Chlorine is the most commonly used and most cost-effective pool sanitiser. You can get it in liquid, granular and tablet form from Pool Chemicals Direct.  Granules require pre-mixing before adding to the water to be distributed by your pool’s filtration system. Liquid chlorine can be added directly into your pool’s water. Tablets can be added to a floating chlorine dispenser or directly into your pool’s skimmer basket and are the easiest way to ensure an even distribution and constant supply of chlorine. If your pool is outdoors and gets a lot of sunlight you might need to use a chlorine stabiliser (cyanuric acid) to prevent UV light from breaking down and burning off the chlorine in your water. A properly stabilised pool will reduce its chlorine consumption by 50 – 80%. Chlor Save is available from Pool Chemicals Direct.

Bromine is the most popular alternative to chlorine. It is just as effective at killing bacteria and more effective at killing algae. Bromine also is considered to be softer on swimmer’s skin than chlorine which is beneficial to people with naturally sensitive skin. Bromine is very sensitive to UV light so if your pool or spa is exposed to a lot of sunlight the chemical will degrade and dissipate quickly. It also can’t be stabilised the way that chlorine can with cyanuric acid. Bromine is available in a tablet form from Pool Chemicals Direct and should be added to the pool or spa’s water using a chemical feeder to dissolve the tablets.

A salt water chlorinator will generate controlled amounts of chlorine from dissolved salt in your pool’s water. Chlorinators takes dissolved salt and splits it into hypochlorous acid and sodium hypochlorite which are the chemicals responsible for cleaning the water, destroying bacteria and preventing algae growth.  Pool Salt is available from Pool Chemicals Direct,

Water balancers

Water balancing chemicals ensure your chlorine, pH and alkalinity levels are within the prescribed levels. To keep your pool’s water in balance you should test several times per week. 

pH Increase (sodium carbonate or soda ash) is used to control the acidity of your pool’s water and increase the pH level to the ideal range of 7.2 – 7.8. If pH levels are too low, the pool water can irritate your eyes and skin, increase chlorine loss and wrinkle vinyl pool liners. pH Increase comes in powder form and is available from Pool Chemicals Direct.

pH Decrease (sodium disulfate or dry acid) is used to lower the pH of the pool water to the ideal range of 7.2 – 7.8 and control the alkalinity of pool water. If pH levels are too high, the pool water can irritate your eyes, make the water cloudy, form scales and decrease the effectiveness of chlorine. pH Decrease is most commonly found in powder form and is available from Pool Chemicals Direct.

Calcium hardness increaser, as the name suggests, increases the total hardness of the pool water. Pool water deprived of calcium becomes aggressive and can etch the pool walls and floor. Available in granular form from Pool Chemicals Direct.

Speciality chemicals

Every pool will also need other chemicals to help keeping it looking its best and fight things like algae, cloudiness and staining. There are many speciality chemicals that will come in handy for every possible pool problem.

Algaecide won’t completely kill algae, but it is another layer of protection. Keeping the chlorine level in your pool where it should be will keep algae at bay, but when water becomes unbalanced algae sneaks in and an algaecide can help control algae growth.

Clarifiers can help clear up a cloudy pool by removing finely suspended particles from cloudy and murky water that the filter can’t normally clean. 

Flocculants treat the cause of water cloudiness by causing all the clouding particles to clump together and sink to the bottom of the pool ready to be vacuumed up. 

Tile and vinyl cleaners help to prevent and control scale, stain and scum from building up around the water line or on pool equipment and accessories.