Blog Articles

bubbles 3.png
bubbles 1.png
bubbles 1.png
bubbles 3.png
bubbles 1.png

The Secret Tango of Pool Chemistry

Wouldn’t it be great if you could just fill your pool with water, and then never have to worry about algae growing, or bacteria building up, or the water just becoming a breeding ground for all kinds of nasty contaminants and organisms? Yes, testing the water and adding pool chemicals regularly might be time-consuming and tedious, but it’s absolutely necessary.

A little preparation means a lot less fixing later when your pool becomes overgrown with algae and the water so unbalanced that the only solution is to drain it and start fresh. While keeping your pool clean and properly sanitized may not strike you as fun, it also doesn’t have to be difficult. All it takes is some basic pool chemistry knowledge, the right equipment and chemicals and a desire to keep your pool clean and swimmable condition.

POOL CHEMICALS - the partners that make up the tango

You could diligently fill your pool with fresh water and skim and brush it every day, and the water can and will still get dirty.

Leaves, twigs, flowers, seeds, pollen, dust and other debris continuously fall into your pool. Insects take their final swims in it and birds fly overhead and bomb it. And every time someone swims, they leave behind body oils, hair, dead skin, shampoo, soap, everything we humans put on our bodies and slough off on a daily basis. Water-loving dogs trample mud into the pool in their eagerness to shed their hair, gob and salivate into the water. Not to mention that the pool seconds as a lavatory for nonchalant bathers (wink, wink). The list goes on.

The only thing keeping those contaminants from turning your pool into a black swamp is your sanitiser, probably the single most important pool chemical you’ll ever use. And in order for the sanitiser to work, other water factors must be balanced: pH, alkalinity and calcium hardness.

Finally, you’ll add pool chemicals to treat algae, to clear your pool and to prevent staining if you use borehole water with high metal levels.

All these factors must dance together in perfect tango harmony in order to create perfectly balanced pool chemistry so that you can swim with peace of mind. So, knowing what to use, and when and how to use it, is vital!

This is the secret tango of pool chemistry and these are the tango partners.


Regardless of the type you use, the sanitiser’s job is to keep the water, well… sanitised and safe. This means free of bacteria, viruses, algae and other nasty things that can grow in untreated pool water. You have a few sanitisers to choose from.


The most popular pool sanitiser due to its efficacy and low cost is chlorine.

Chlorine sanitises your pool by oxidizing contaminants. It enters molecules and destroys them from the inside out. Chlorine is effective at killing viruses, bacteria and algae and will also prophylactically prevent algae from growing to begin with.

Chlorine comes in three forms:

  • Granular: You pour chlorine granules into your pool water where they dissolve and chlorine is distributed around the pool by your pool's circulation and filtration system. This isn't a very effective method though. It is time-consuming and there is a chance the chlorine won't be evenly distributed leaving pockets of not-so-sanitised water around your pool, as well as pockets of super-chlorinated water, which can damage your pool lining.

  • Floater: This is slow release granular chlorine that is sold in it's own container/dispenser, ready to use and gradually and consistently supplies your pool water with chlorine.

  • Tablets: Chlorine tablets can be added to a basket-type floating chlorine dispenser and act in the same manner as a floater.

Beluga Tip: The ideal chlorine level in your pool water is 3 parts per million (ppm). Anything less than that, and your pool water isn’t really clean. Anything more than that is unnecessary and wasteful, and you need to dilute the water a little or hold off on adding chlorine for a while until the desired level is reached. When it comes to chlorine, there is such a thing as too much of a good thing.

You’ll also find two types available: stabilised and unstabilised chlorine.

Stabilised Chlorine If you have an outdoor pool, which most of us do, to prevent the sun from burning off the chlorine in the water, especially in our harsh South African climate you need stabilised chlorine. It has cyanuric acid also known as chlorine stabiliser or pool stabiliser, added to it.

The cyanuric acid protects the chlorine, so it stays in the water three to five times longer, making it more effective at keeping the pool clean so that you don’t have to replace the chlorine as often. This saves you money and time!

Beluga Tip: If the chlorine you buy doesn’t specifically say “stabilised” on the label, check the active ingredient. If it’s Trichloro-S-Triazinetrione or Trichlor, it’s stabilised. Yes, reading pool chemical labels is a thing…

Important: Again, there is such a thing as too much! Be careful of using stabilised chlorine for too long. If too much cyanuric acid builds up in your water, it will reduce the chlorine’s effectiveness and can even stall it all together called Chlorine Lock. If this happens, the only way to reduce the level is to dilute your pool water by removing some and replacing it with fresh water. Or, if there’s so much cyanuric acid that diluting the water won’t help, you may have to drain the pool altogether.

Unstablised Chlorine This type of chlorine is vulnerable to the sun’s ultraviolet rays, especially in South Africa. UV rays burn the chlorine out of the water, reducing its sanitising ability. This means you’ll have to add more chlorine to your pool more often, which means you’ll be spending more money and time.

So why would you ever want to use unstabilised chlorine? Well, if you have an indoor pool, you don’t have to worry about the sun eating up the chlorine. And if you are struggling with high cyanuric levels you don’t want to be using stabilised chlorine for a while which will be compounding the high levels even more.

It can also be used as pool shock, especially since you shock your pool at night (you do, don’t you?), so again, there’s no worry about the sun.

Beluga Tip: If the chlorine you buy doesn’t specifically say “unstabilised” on the label, check the active ingredient. If it’s Calcium Hypochlorite or simply Cal-Hypo, it’s unstabilised. This type of chlorine is most often available in granules rather than tablets.

Add the Cyanuric Acid Yourself Rather than using stabilised chlorine and risking the level of cyanuric acid building up too much, you can always opt use unstabilised chlorine and add cyanuric acid or stabiliser to the pool yourself. This gives you more control over the amount of cyanuric acid in your pool water.

Beluga Tip: The ideal cyanuric acid level in your pool water is between 30 and 50ppm.


During the oxidation process, chlorine dissipates and eventually becomes a waste product called chloramine. When you approach a pool and you smell that distinctive “pool smell,” it’s not that the chlorine level is too high (many people mistakenly believe this), it’s the chloramine, indicating that in fact your chlorine level is too low.

Chloramine is also what stings your eyes and dries your skin when you swim. It’s also not the best thing to breathe in.

To keep chloramines under control, you must add chlorine to your pool on a regular basis, according to how much it needs, which you’ll determine by testing your water (remember, your free chlorine level should be between 1 and 3ppm). And if the chloramines get really bad, and your pool really smells of chlorine, you’ll need to shock it to get rid of them.

The good thing is, you’ll be shocking your pool on a regular basis anyway (Right? Right!), so that will help manage chlorine and chloramine levels.

Salt Water Pools

Although this method of sanitisation has been around since the 1970s, this sanitiser system is fast becoming a popular alternative to the traditional chlorine pool in South Africa, mostly because it is more low maintenance and more cost effective in the long run. Salt water systems are also more gentle on the hair, skin and eyes as well as not being prone to chloramines.

However, while you may have been led to believe that all you need to do to maintain a salt water pool is throw in some salt every few weeks, it’s actually a bit more involved than that. Don’t fall victim to the mindset that low maintenance is no maintenance. Your pool water still needs to dance that tango to be well balanced so that the sanitiser can act effectively.

The most important thing to understand is that salt water pools are not actually chlorine free. A salt chlorinator creates the same kind of chlorine used in a chlorine pool by splitting the salt molecule (NaCl) into Sodium and Chloride, it does not balance your water. You’ll still need to test your water regularly, sometimes adding chemicals to balance it. These chemicals are the same ones you’d use in a chlorine pool.

Interestingly, salt water pools require higher levels of cyanuric acid or stabliser, so aim to keep the level between 70 and 80ppm, per most saltwater system manufacturers.

Beluga Tip: Always use good quality pool grade salt. The most important aspect of choosing pool salt is impurity levels, that is, minerals and metals contained in the salt. If you dump salt full of impurities into your pool water, you’ll spend time and money fighting imbalances, metals, or calcium carbonate build up.

Now that you have the basics of sanitisers down, let’s look at some of the other facets of balanced pool chemistry, and the pool chemicals that will help you achieve them.


Next to chlorine, this is probably the second most important partner in the tango. This pool chemical’s main job is to prevent pH from drastically moving up and down the scale by acting as a buffer, absorbing major changes to the water before they can affect the pH.

To keep alkalinity steady, keep a supply of alkalinity increaser, like Bicarbonate of Soda, on hand. If both your pH and alkalinity are low, alkalinity increaser, like Soda Ash, will raise both, another reason to adjust alkalinity first.

Alkalinity decreaser isn’t available as a separate pool chemical, so if your pH and alkalinity are both high a pH decreaser, like pool acid, will lower both. Lower the alkalinity first by adding pH decreaser with pool acid. Yes, this will also lower pH levels. Once the alkalinity is where it needs to be, then work on bringing the pH back up with pH increaser with Soda Ash.

This situation can be tricky to correct, and it may take several tries to get both levels back to normal, so make adjustments gradually to avoid throwing things even further out of sync.

Beluga Tip: The recommended alkalinity range in your pool water is 80ppm to 150ppm, with 120ppm being ideal.

Important: Because alka