SwimmingPoolsThailand - CHLORINE GUIDE 

Links to contents:

Introduction
Total chlorine
Chlorine demand and Chlorine residual
Types of chlorine
Calcium Hypochlorite
Powder
Granules
Tablets
Dosing
Examples
Superchlorination ('shocking')
Ozone

Every swimming pool in Thailand pool has a different requirement. The Association of Pool and Spa Professionals recommends free chlorine levels for both swimming pools and hot tubs be kept between 2.0 and 4.0 ppm.

The Center for Disease Control recommends free chlorine stay above 1 ppm in pools and 3 ppm in hot tubs. Recommendations, or suggestions for use made here are intended for the assistance of our customers and are offered as is, without any guarantee for accuracy. They are based upon decades of proven best practice for pools, regional and/or state laws, plus our 45 years experience and judgement; they must not however be regarded as amounting to a legal warranty or as involving any liability on our part and must be read in conjunction with and subject to our conditions of sale.

Most swimming pools in Thailand are sanitised (disinfected) by using chlorine. This is done by manually adding powder, granules, or tablets in the correct proportions or automatically by a salt water chlorination system. Chlorine eliminates bacteria and algae by disinfecting (killing) action, it also oxidizes (chemically destroys) other materials such as dirt and chloramines.

Whatever method of introducing chlorine to your pool, the level must be checked every three days. Semi automated salt water chlorinators or ORP-driven systems do not relieve of the responsibility for regular checks.

It is essential to maintain the pH at a level within 7.2 and 7.6.  Outside these parameters, chlorine will not work. pH should be tested every three days and adjusted as required using pHminus  or pHplus.

 Testing: For most residential pools a simple, inexpensive test kit for both chlorine and pH is adequate.

TOTAL CHLORINE

This is the total of free chlorine and combined chlorine. The traditional, inexpensive OTO test kit (which also includes phenol for testing pH), displays the value of total chlorine in shades of yellow. They measure true chlorine because it is easier to test for than free chlorine and combined chlorine. In most domestic pools provided the pH level is correct, it is safe to rely on this simple test. These tests for chlorine and pH are more reliable and cheaper than test strips.

When chlorine (in any form, including by salt water chlorinators) is added to water, a weak acid called Hypochlorous acid is produced. It is this acid, not the chlorine, which gives water its ability to oxidize and disinfect. Proper chlorination and filtration give pool water its clear, sparkling appearance. Filtration alone does not kill bacteria or prevent the growth of algae. Only filters using graded sand, crushed glass, Zelbrite, or D.E. powder are suitable for pools. Despite the claims made by the manufacturers, cloth type skimmer-filters do not provide sufficient filtration.

CHLORINE DEMAND and FREE CHLORINE RESIDUAL

As chlorine is introduced into pool water, a portion is always consumed during the processes of disinfection and oxidation. That portion of available chlorine consumed is referred to as chlorine demand. The hypochlorous acid left after the chlorine demand has been satisfied is referred to as the free chlorine residual. This is what we read when we test the pool for chlorine. US and Australian laws require that the free chlorine residual be at least 1.0 ppm throughout the pool at all times (1.5 ppm if stabilized chlorine is used). It is recommended that a residual of 1.5 - 2.5 be maintained with unstabilized chlorine; 2.0 - 2.5 with stabilized chlorine. (See Cyanuric Acid below)

TYPES OF CHLORINE

Chlorine exists as a solid, a liquid and a gas. The strength of each type is determined by the amount of chlorine within the material that is effective both as a disinfectant and an oxidizer. Chlorine for swimming pools is available from SwimmingPoolsThailand in most types and in convenient quantities for shipping.
Liquid chlorine (sodium hypochlorite) contains 12‐16% available chlorine. (By contrast, household bleach generally contains about 5% available chlorine.) Generally not appropriate for pool unless an automated ORP system is installed.
Solid chlorine (powder, granules, tablets) - the most common form
Chlorinated Isocyanurates‐ varying percentages of available chlorine such as T.C.C.A for pools (90%). Calcium Hypochlorite‐ 65‐75% available chlorine. Lithium Hypochlorite ‐ 30‐35% available chlorine
Gaseous Chlorine contains 100% available chlorine. Produced by saltwater chlorination systems. This substance is highly toxic and therefore requires special procedures when it is used.

POWDER

Our PoolChlor chlorine powder is the best quality and value currently available in Thailand. (see 'other brands' below). Available in 5Kg, 20Kg, 50Kg. Powder dissolves quickly and is used quickly. Best for use in emergencies and when filling or refilling a pool, and for shocking.

GRANULES

Our PoolChlor granulated chlorine is the best quality and value currently available in Thailand.(see 'other brands' below)

TABLETS

Our PoolChlor tablets are the best quality and value currently available in Thailand. Available in 1Kg, 5Kg, 20Kg, 50Kg. Packed in 1Kg PVC tubes inside the buckets or barrels.Generally, as powders and granules dissolve very quickly, tablets are not used for the regular twice weekly addition of chlorine to maintain the correct level. Typically, a 3-inch pool chlorine tablet is designed to chlorinate from 28m³ to 38m³ (7,500 to 10,000 gallons US) of water per week (typically about 4 x 6m to 4 x 9m small dip pool), meaning it'll take seven days to dissolve.

Water moving over chlorine tablets, as happens in a chlorinator or with tablets designed to be placed in the skimmer, causes them to dissolve more quickly. To use the right number of tablets, always round your pool volume up to the nearest unit of 5,000 gallons. For instance, if your pool has a capacity of 75m³ (20,000 gallons,) you would add four chlorine tablets. But if your pool holds just 60m³ (16,000 gallons,) you'd still use four, three-inch chlorine tablets.

Slow dissolving chlorine systems and automated chlorine dispensing systems will only work when the pool water is already boosted to the correct levels of both chlorine and pH. In other words, tablets and auto systems maintain what is already there.

Tablets are obviously slightly more expensive than powder or granulated chlorine, but the value is in their convenience and ease of use once the pool water is set up correctly.

DOSING

Chlorine dosage should be between 1.5 and 2 mg of chlorine / liter.
Thus, for a 40m³ pool or 40 000 liters, must be permanently chlorine 80g or at least one or two 200gr tablete every 7 days. Always calculate the volume to include the volume of the balance tank in overflow pools. The chlorine level should stay between 1.0 and 3.0 parts per million (ppm) to maintain a healthy pool.

Chlorine dosage 5 gr per m3 (1,000 l) per day.

Examples

32 m3 (4 x 8, 2 x 10,etc) = 160gr/day

40 m3 (8 x 5, 4 x 10, etc.) = 200 gr/day

70 m3 (6 x 12, etc) = 350 gr/day

100 m3 ( 6 x 18 etc.) = 500 gr/day

200 m3 (10 x 20 etc.) = 1,000 gr (1 kg)/day

300 m3 (12 x 25 etc.) = 1,500 gr(1.5 kg)/day

400 m3 (20 x20 etc.) = 2,000 gr(2 kg)/day

800 m3 (20 x 40 etc) = 4,000 gr(4 kg)/day

Monitor chlorine levels at least once a week.

SUPERCHLORINATION (ʺShockingʺ)

Shock chlorination is a process used in swimming pools to reduce the bacterial and algal residue in the water. Shock chlorination is performed by mixing a large amount of sodium hypochlorite , which can be in the form of a powder or a liquid such as chlorine bleach, into the water. The common advice is that the amount added must raise the level of chlorine up to 10 times the level (in parts per million) of chloramines present in the pool water-this is "shocking".

A lesser ratio is superchlorinating. Water that is being shock chlorinated should not be swum in until the sodium hypochlorite count in the water goes back down to 3ppm or less. Commercial sodium hypochlorite should not be mixed with commercial calcium hypochlorite, as there is a risk of explosion.

Some of the available chlorine will react with nitrogen‐containing compounds to form chloramines (combined chlorine). A common source of nitrogen is ammonia, produced from perspiration and urine. Chloramines give off a strong chlorine odor and are irritating to the eyes.

The presence of these two conditions leads many people to believe that there is too much chlorine in the water; actually just the opposite is true. In order to eliminate the chloramines the pool operator must raise the chlorine residual to 5 to 10 times the normal level. This procedure, called superchlorination or ʺshockingʺ, oxidizes the chloramines, leaving only the free chlorine.

Depending on swimmer loads, it is recommended that a pool be superchlorinated as often as once a week in hot weather and once a month otherwise, in order to control the formation of chloramines. (Note: bathing should be prohibited until normal levels are restored.

Calcium hypochlorite Ca(ClO)₂ is a non-stabilised (no CYA) fast-acting and commonly used to sanitize public swimming pools and disinfect drinking water. Generally the commercial substance is sold with a purity of a 65 to 73% with other chemicals present, such as calcium chloride and calcium carbonate, resulting from the manufacturing process. Non stabilised - use if you do not want to increase the CYA level. Best for shocking pools that are manually chlorinated with T.C.C.A powder, granules, or tablets, NOTE: Frequent use of Cal Hypo will increase the Calcium Hardness of the water.

Sodium dichloroisocyanurate C₃Cl₂N₃NaO₃ is a stabilised, chemical compound widely used as a cleansing agent and disinfectant. Ideal for for shocking pool with salt water chlorinators, or starting a new pool or a newly filled pool. It is mainly used as a disinfectant, biocide and industrial deodorant. It is found in some modern water purification tablets/filters. In these applications, it is a slow-release source of chlorine in low concentrations at a relatively constant rate. As a disinfectant, it is used to sterilize drinking water, swimming pools, tableware and air, and to fight against infectious diseases as a routine disinfection agent.

OZONE

Use of chlorine with ozone

Some salt water chlorinators are available with an ozone gererating accessoy. Ozone is an excellent alternative, a much more effective oxidizer than chlorine shock.

Use of UV with ozone

SwimmingPoolsThailand also offers economical UV systems that can be installed to supplement or even replace the use of chlorine. In many cases they can reduce the traditional use of chlorine by up to 95%. As a disinfectant, UV is used to sterilize drinking water, swimming pools, tableware and air, and to fight against infectious diseases as a routine disinfection agent.

Products



Nissan 90% TCCA stabilised chlorine GRANULAR. Very high quality. Available in 50 Kg and 20 Kg drums.



Nissan 90% TCCA stabilised Chlorine POWDER. Very high quality. Available in 50 Kg and 20 Kg drums. 

Nissan Hi-Lite 90% TCCA stabilised shock chlorine POWDER



Nissan Hi-Lite 90% TCCA stabilised shock chlorine GRANULAR  and POWDER. 7 kg. Very high quality. 



PoolChlor 90% TCCA stabilised chlorine available as GRANULAR, POWDER, and 3" TABLETS. The next highest quality brand of chlorine available in Thailand. No wastefull fillers or binders. 

 



Dichlor 60%. SDIC stabilised poolshock GRANULAR Ideal for for shocking pool with salt water chlorinators, or starting a new pool or a newly filled pool.



Calcium Hypochlorite 65% non-stabilsed pool shock POWDER Non-stabilised fast-acting chlorine 65% for shocking pool water without increasing the CYA level.