How To Add Hydrochloric Acid To A Swimming Pool

I will explain here what the hydrochloric acid is used for in the swimming pool: by descaling and the dosage to lower the TAC and the pH.

Hydrochloric acid is a dangerous chemical compound. It should be handled with care, especially gloves and protective glasses. For the treatment of the swimming pool, one can often use other products, less dangerous.

To use it, it must be diluted in a large volume of water: 30% acid and 70% water. Always pour the acid into the water and never the other way around.

Hydrochloric acid is corrosive to metals. So the pool pump and other equipment are not going to like it at all.

After putting hydrochloric acid in the pool. you should avoid bathing for 24 to 48 hours.

Why Use Hydrochloric Acid in the swimming pool?

For the maintenance of the swimming pool, hydrochloric acid can be useful for 3 reasons:

  • lower the pH
  • lower the tack
  • Descaling

Use Hydrochloric Acid To Lower the PH

The hydrochloric acid allows to lower the pH of the swimming pool, strongly. The dosage of hydrochloric acid in the swimming pool is approximately 10mL per m³ to lower the pH by 0.3. It is very powerful!

For comparison, pH-lowering products containing sodium bisulfate or sulfuric acid have a potency of about 0.15 per 10mL per m³.

Like any product that lowers the pH, hydrochloric acid also lowers the TAC. Compared to products lowering the pH, hydrochloric acid will have an even greater impact on the TAC. Moreover, the dosages to be carried out depend on the TAC of the swimming pool: the higher the TAC, the more chemical product is required.

Use Hydrochloric Acid To lower the TAC

Hydrochloric acid helps to lower the TAC of the pool. It is even very effective in this area. The hydrochloric acid dosage is approximately 2mL per m³ to lower the pool’s TAC by 1 ppm (0.1 ° F).

Use Hydrochloric Acid to Descale the Walls of the Swimming Pool

Hydrochloric acid dissolves limestone. It is sometimes used for very scaled toilets.

In a swimming pool where the water is particularly hard, limestone can form on the walls and at the bottom. To prevent this problem, there are lime sequestering agents. To correct the problem, one can use hydrochloric acid.

If the pool is very calcified, then empty the pool and spray hydrochloric acid on the walls, little by little, then wipe with a sponge.

I also recommend putting hydrochloric acid 40cm away from the coping, leaving it to stand overnight and then turning on the filtration for 48 hours, without swimming.

How To Shock Your Swimming Pool

The shock treatment of a swimming pool is for corrective purposes. If your water has lost its transparency and its crystal clean appearance, if it has changed color, tending towards green and if you are concerned that it will get worse in the next 24 hours, shock treatment is the best choice.

This is the last winning option in the face of water that has turned, before considering emptying, even partial, of the pool. Following a non typical event, a shock treatment may be necessary to restore clear and crystalline water.

Given the chemical load implemented by the shock treatment, its recommend shocking the pool at least once every 2 weeks in the middle of summer. 

Basically, it depends above all on the care taken in maintaining your pool and the water it contains. Regardless, if the water begins to cloudy or turn green, don’t wait and act as quickly as possible.

For health reasons, it is not recommended to bathe during shock treatment . With the little ones, you must strictly prohibit swimming, explaining why. Depending on the case, this can last for 48 hours.

Why shock treatment?

If the maintenance and filtration of the pool are properly carried out, then shocking a pool will not need to be done.

The water can then cloud quickly and be overrun with algae in less than 48 hours, taking on a bizarre coloring that is unappealing to swimming and potentially dangerous for your pool.

Faced with this type of inconvenience, the shock treatment is a radical solution that allows you to attain healthy and clean water . Its chemical load eradicates all microorganisms, bacteria, viruses, algae, mosses or fungi that have taken possession of the premises.

When do you need to do shock treatment?

Although this is an exceptional procedure, as the water ages (chemists speak of the age of water), shock treatment will become less rare. Its goal is to use chemicals to find conditions suitable for swimming.

These are the times when a swimming pool will need shock treatment.

  • – After a complete emptying of the pool.
  • – After wintering, when the swimming pool is put back into service.
  • – After a meteorological event: thunderstorm, storm, strong gales, extreme heat.
  • – Following a proliferation or invasion of algae: whatever the reason.
  • – Following a strong use of the pool: a large number of bathers.
  • – Following a bacterial or viral infection of a swimmer to eliminate any risk of contamination.
  • – Before winterizing the pool, at the end of the season. – When put back into service in the spring.
  • – After the first filling

What products should be used to shock your swimming pool.

With a little experience, you will know the right products for you.

If this is the first time or a pool you don’t know, remember that there are no dumb or unnecessary questions. It is better to inquire and ask when you are not sure of what you are doing, whether it is from a specialized store, a forum, a loved one. You’ll save time, money, and less stress about the condition of your pool water.

Chlorine and Bromine shock are the most widely used.

If you usually disinfect your pool with chlorine, use shock chlorine . It is rapidly dissolving chlorine, not stabilized in powder, pellets or granules, based on Calcium Hypochlorite or Sodium Hypochlorite (bleach).

If you usually disinfect your pool with bromine, choose shock bromine .
You can also use shock chlorine (Calcium hypochlorite, Sodium hypochlorite) but you probably won’t.

Active oxygen is the most common alternative.

Pay close attention to incompatibilities between products.

If you are using another form of pool sanitizer, then active oxygen products will often be recommended. Knowing that active oxygen is also very effective in shocking a swimming pool usually treated with chlorine or bromine.

If treating with PHMB, use active oxygen, as it is incompatible with chlorine or bromine.

If treating with copper/silver ionizer or vegetable ceramic, prefer shock chlorine (calcium or sodium hypochlorite) or active oxygen. Do not use shock bromine.

If treating with Ozonator, prefer shock bromine or shock chlorine (calcium or sodium hypochlorite)

If treating with UltraViolets, prefer shock bromine, shock chlorine, or calcium hypochlorite. Do not use active oxygen if and only if the pool is larger than 90m3, the pool is sheltered and the water temperature is over 30 ° C.

How to Start Shock Treatment?

1 – Prepare the pool water.

– Stop all swimming: explain to the little ones if necessary and close access to the pool if possible.
– Uncover the pool: it is probably already uncovered, otherwise, remove the cover or fold up the roller shutter. Shock treatment requires a visual check several times a day. If the inside of the cover or shutter seems dirty, spray them with water.
– Remove the accessories and objects that are in the water: toys, pipes. Clean and rinse them.
– Remove any large debris using a net and empty the baskets of the skimmers and the pump pre-filter.

– (not compulsory) Clean the swimming pool: walls, bottom, water line. If the water is really dirty and you cannot see what you are doing, it is wiser to wait until the treatment has started to act: risk of degrading the coating. Knowing that once the shock treatment is finished, it will be necessary to clean the walls, bottom, waterline, and the submerged parts (skimmers, nozzles, bung, plugs, and various equipment) again. It’s up to you to assess the situation …

– Check the condition of the filter (pressure in particular) and clean it if it seems too dirty to you: washing/rinsing if a sand filter or replacing the cartridge/bag.
– Analysis and adjustment of the water balance according to the shock treatment used, in particular the pH. Also, check the total alkalinity (TAC) and the lime content (TH). Make sure the settings are correct and don’t do anything else until they are: the most important is the pH.

2 – Run the pump continuously until the water has a gray/blue appearance.

– Put the shock treatment products in place. Read the instructions before proceeding. Check that there is no incompatibility.
– Put the filtration in continuous operation.
– Wait for the treatment to take effect by cleaning/replacing the filter if necessary (stop filtration during these phases).

Depending on the state of the water, it can last from 48 hours to a few days. Some water catching can take 2 to 3 weeks.

During this time, you must continue to check the water (pH, disinfectant level) and rinse the filter if it begins to build up pressure (rely on the pressure gauge).

3 – Flocculation and cleaning of the pool to finish.

If the water has become clear again but remains cloudy, use a flocculant or clarifier to conglomerate the residue and remove it more easily through filtration. It may be the remains of dead algae in suspension. Use only if the water has not become clear and crystalline again.

Once finished,
– clean the swimming pool: walls, bottom, water line, submerged parts, using brushes, vacuum cleaner, and/or robot cleaner to find clear water.
– recheck and re-clean the filter if necessary before returning to normal filtration mode.

If you need to, don’t forget that there are companies specializing in pool maintenance. They can intervene occasionally or take charge of the complete maintenance of your swimming pool.

How To Regulate the PH of a Pool

The pH level of the water is a very important value for safe swimming and enjoying clean, crystal clear water.

Knowing how to adjust the pH levels of a pool is very important for the safety of swimmers. Along with chlorine, pH is a fundamental element for the water to be clean and clear.

But, in addition, keeping the pH at the appropriate level prevents the formation of microorganisms such as bacteria and fungi.

The pH is an index that indicates the acidity or alkalinity of the water. Normal values ​​should be between 7.2 and 7.6. This index must be measured together with that of chlorine since both the pH and chlorine are responsible for making the pool water suitable for swimming. Most experts agree that the ideal value for chlorine is 1 ppm (that is, parts per million) and the recommended alkalinity level is 125-150ppm.

If the chlorine content is high you do not smell anything or see anything suspicious in the water that alerts a person to it, because the chlorine does not smell. What smells is the reaction of the chlorine to sweat or urine, which causes the appearance of chloramine, which is highly toxic and dangerous to a person’s health.

Therefore, if the pH level is not adequate and the chlorine is high, the damage to a person’s health is serious.

For its part, alkalinity plays a very important role in controlling the pH, because if it is not correct, you will not enjoy swimming because the water will not be clean and clear.

Therefore, whether the pH is above ​​or below the normal values, the problems it causes both in the water and in our body’s is serious. Hence, it is necessary to check its levels frequently with various pool treatments.

What will happen if the pH level is below the recommended value?

If the pH value is below 7.2, the water will be acidic. The symptoms of a swimmer are itching and stinging of the eyes and nose, dryness, irritation of the throat, stinging and itching of the skin, irritation, and dryness, appearance of eczema, or redness of the skin can appear.

But not only does your body suffer. The pool equipment can corrode by the acidity of the water, especially those metal parts and those made of cement. It is also normal for the mosaic tiles to detach themselves from the walls and bottom of the pool. They could end up floating or be found at the bottom of the pool. This is not safe for a swimmer who could cut themselves while swimming.

What will happen if the pH level is above the recommended value?

If the pH value of our pool is above 7.6, the water will be alkaline. The symptoms of a swimmer are dry and irritated skin. But the biggest problem is the water, which will become cloudy, even greenish, as the algae start to appear. Even if you try to raise the chlorine levels to eliminate them, it will be impossible if you do not regulate the pH level first.

As if that were not enough, the high pH will promote the formation of lime deposits in the pool water. These lime deposits will be embedded in the pipes and other installations, affecting their functionality. The lime will also stick to walls and floors, affecting the appearance, and cleanliness of the pool.

Therefore, to know if the pH level is high we will have to measure it with a test kit that measures both the pH and the chlorine in your pool.

How to raise the pH level of a pool

If the pH level is low, you will have to use ph UP that you can buy in any pool store. There are solids, liquids, and granules and their function is to reduce the acidity of the water.

How to lower the pH level of a pool

If the pH level is high, you will have to make use of a pH DOWN, which comes in the form of both granules and liquids. With the use of the pH DOWN the alkalinity falls and the pH increases in value.

How to make your pool water crystal clear

To ensure that the water in your pool is clean and clear, it is important that the pH level of the pool water is correct, but also that of chlorine. How do you achieve that? By checking the levels regularly. It is important to know that there are aspects such as the effects of the sun, the number of people who are swimming at a certain time, and the remains of sunscreen in the water that destabilize these values. Therefore, it is essential to frequently measure the pH and chlorine levels in the pool.

Can You Swim In A Green Pool?

The question you are asking your self is can I swim in a green pool? The answer is NO. In this article, I will explain why pool water turns green and what that water can do to you if you swim in it.

Why Does Pool Water Turn Green?

1 There is an imbalance in the PH levels of the pool water.
2 The Chlorine levels are too low.
3 The alkalinity levels are too low.
4 The Oxidized Metal quantities example copper is too high. (High acid levels, Metal Components in pool equipment, Copper heater elements)
5 Excessive quantities of Pollen are in the water.

Here’s Why You Should Not Swim In A Green Pool

When your pool is green that means there is an imbalance in the PH levels of the pool. If the PH levels are out this means that the pool water is not sterilized.

When the pool water is not sterilized there is an opportunity for algae, bacteria, and pathogens (microorganisms that can cause disease) to be present and grow.

If this is the case, then if a swimmer has an abrasion on their skin, there is a potential for infection and a possibility of incurring a rash or folliculitis (inflammation of hair follicles).

If the pool water has any form of algae and bacteria in it, it will be the ideal breeding ground for mosquitoes and other insects that thrive in these conditions.

Excessive amounts of oxidized metals can turn a swimmers’ hair green and there is a good possibility that your pool walls will be stained.

High levels of the copper content in the pool water can irritate your mouth, eyes, and nose, cause headaches, nausea, vomiting, stomach cramps, dizziness, and diarrhea.


It is not advisable to swim in a pool with water that is any color than clear blue. There are too many health problems that a person can incur from swimming in a green pool.

Rather sort out the PH levels first. Get the pool water crystal clear so that you and your family can enjoy the pool with no issues.

How To Raise Low Chlorine Levels In Your Pool

Maintaining the correct Chlorine level in a swimming pool is important. If the level drops too low then there is a possibility of Bacteria and Algae Growth in the water.

The correct level of Chlorine in a residential swimming pool should be between 1-3ppm.

If the level is below 1ppm then there is no sanitizer to fight and prevent bacterial growth, which gives the swimming pool a greenish color and is unsafe to swim in.

How To Raise Low Chlorine Level In Your Pool

A thorough clean out of the pool pump basket and weir baskets, a thorough brushing of the swimming pool walls, steps, ladders, and the floor is necessary to get the dirt and bacteria mixed with the water.

Remove leaves and heavy dirt from the pool bottom. Then backwash the pool for 2 minutes and rinse for 20 seconds. This will clean the filter sand, so it is ready for the main filtering of the dirty water.

Then test and correct the PH level of the swimming pool water. The PH level for a Marbelite Pool should be between 7.2-7.6 and a Fiberglass Pool 7.0-7.2.

If the PH level is less than 7.2 in either a Marbelite or Fiberglass Pool Add HTH Soda Ash.

If the PH level is greater than 7.6 in either a Marbelite or Fiberglass Pool Add HTH Easy Acid.

When the PH level is correct then it is very important to also check and correct the Total Alkalinity of the swimming pool water. Total alkalinity is measured by its concentration in parts-per-million (ppm), and the ideal range is between 80-120ppm.

If the Total Alkalinity is low then Add HTH Alkalinity Up. 1kg of HTH Alkalinity Up should raise the Total Alkalinity by approximately 10ppm.

If the Total Alkalinity is high then Add HTH Dry Acid/Easy Acid. Never add more than 250g of HTH Dry Acid/Easy Acid at any one time.

With both the above levels corrected. HTH Granular and Mineral soft can now be added to the swimming pool water. If the pool water is excessively green and it has a sign of green algae then HTH Shock It can be used instead of or with the HTH Granular.

With the pool pump on and set on filter. Add 3 x the normal dose of HTH Granular plus 1 bag of HTH Shock It. Or just add 1 bag HTH Shock It. Add these chemicals around the sides of the pool in the early evening.

Test and correct the PH levels every 12 Hours until the swimming pool water is clear and the Chlorine Level is between 1-3ppm.