The Use of a Sanitizer

 Let’s assume that the water in your pool is well balanced chemically, but there are still bacteria, algae and contaminants in the water. Therefore, you need a product to purify your water.

Chlorine is the most common product on the market. It is also used by municipalities to clean up the water you drink. It is available in several formats: granules, tablets, cleaners, liquid and gaseous form. Chlorine can be stabilized or unstabilized. The advantage of stabilized chlorine is that it is not affected by UV rays and remains in the water longer.

Of course, there are also other types of purifiers on the market such as bromine, hypochlorite, lithium, trichlor, dichlor, etc. to name a few. This article focuses on the most popular: chlorine.

The daily dosage

If you use a distributor of chlorine or chlorine pucks in the skimmer, you should perform your tests and make sure the chlorine levels are within the limits. But if you use chlorine granules and chlorine in liquid form, then you will use one dose daily to maintain the levels:

1.0 to 3.0 ppm for residential or commercial pools;

3.0 to 5.0 ppm for residential or commercial spas.

The ideal time of day to add chlorine

You should add it by late afternoon because then it remains in the water throughout the night and can fight bacteria and algae better due to the lack of sunlight.

Water low in chlorine: <1.0 - Rapid formation of algae and bacteria, strong smell of chlorine, can cause disease. 

Normal chlorine levels: between 1.0 and 3.0  - Ideal range for the control of algae and bacteria.

Water etching in chlorine: >3.0 - Discoloration of hair and bathing suits, potential eye irritation.

Approximate dosage                                       Approximate dosage

of granules or tablets (with stabilizer)             of granules or tablets (without stabilizer)
30 g per 10,000 liters of water                       60 g per 10,000 liters of water
Super chlorination (when the temperature exceeds 32 ° C)
Super chlorination is advisable if the temperature exceeds 32 ° C (90 ° F) or in case of heavy use of the pool, heavy rain, winds that bring debris or pollen in the water. Increase the dose of chlorine so that the concentration increases to 3.0 to 5.0 ppm for pools or 5.0 to 7.0 for spas. Thus, bacteria and algae are fought against. Return to the normal dose when the temperature drops below 32 ° C (90 ° F).
Shock treatment (normally every 2 weeks or one week when the temperature exceeds 30 ° C)
Over time it happens that the chlorine combines with organic wastes. Then, the amount of free chlorine decreases and thus so does its ability to fight bacteria and algae. The combined chlorine (also called chloramine) produces a bad smell. This characteristic odor suggests that there is too much chlorine in the water. The reality is quite different. This odor means that the dose of chlorine needs increasing for the amount of free chlorine to increase, too, as this helps get rid of the chloramine and finally the bad smell of chlorine. Some bacteria or algae can resist the daily dosage. This is why it is important to conduct regular shock treatments.

Shock treatment helps to solve several common water problems.
When should you apply shock treatment?
Increase the chlorine dose in the evening to obtain 10 ppm (about 5 times the daily dose).
Shock treatment every 2 weeks – Decrease the chlorine level to 3.0 or less before swimming. The ideal time for shock treatment is when it rains or it is too cold for swimming.
Shock treatment every week - When the water temperature exceeds 30 ° C (85 ° F)
When the water temperature falls to or below 30 ° C, you can go back to the 2 weeks cycle.

Shock treatment is necessary:
- In early and late season. 

- If you have forgotten to add chlorine in recent days.

- If there is algae, if there was a storm, if there are many swimmers.

Do not use stabilized chlorine or chlorine pucks for shock treatment. Liquid chlorine may be used but it has the tendency to raise the pH levels and contains only 12% chlorine (bleach contains 6% chlorine).

Stabilizer (cyanuric acid)
Concentration: 30 to 50 ppm

The strong ultraviolet rays of the sun destroy much of the free chlorine in your water. A product like cyanuric acid, also known as stabilizer or conditioner, will form an invisible layer on the surface of the water that blocks the UV rays. This is an excellent investment because it allows you to save a lot of chlorine and you do not have to chlorinate needlessly every day.