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Sanitizers

disinfection of pool water

It should be noted that disinfection of pool water depends heavily on pH and Alkalinity balance. Without those two factors being in the proper range, sanitizers or disinfectants as they are known cannot properly perform the function of killing bacteria. Additionally, proper balance of the water pH, Alkalinity and other chemistry factors will provide water that will not damage pool components and is non-irritating to swimmers. Apart from this it is then necessary to provide for disinfection of the water to prevent the spread of disease organisms from person to person and prevent unwanted growth of bacteria and algae in the pool.


Chlorine
The most commonly used disinfectant for swimming pools is chlorine. In its elemental form chlorine is a heavy greenish yellow gas which is so toxic that is has been used as a weapon in chemical warfare. Because of the extremely high potential for injury or death from improper use of chlorine gas, a number of chlorine compounds have been formulated to provide chlorine in forms that can be handled and used safely by swimming pool operators.


forms of chlorine commonly used


"Dry or Powdered Chlorine" = Calcium Hypochlorite: Dry granular or pelletized 65% available chlorine. Look for our product called "Quick Dissolve" by E-Z Clor.

NOTE: There are many brands and qualities available of Chlorine products; we sell and highly recommend E-Z CLOR products for their quality and rigid standards for pool safety and effectiveness.


Advantages:

Disadvantages:

Relatively cheap

Not stabilized - may lose strength if not tightly covered.

Can be mixed into solution for feed pumps

Does not dissolve completely - leaves residue

Can be used in some specially designed erosion feeders

Does not dissolve completely - leaves residue

 

High pH (11.7) raises pH of pool

 

Highly reactive - may cause fires


Sodium Hypochlorite: Liquid bleach 12.5% available chlorine. This is the typical pool chlorine that you will find for sale at Poseidon Pools.

NOTE: Beware of cheaper brands of sodium hypochlorine sold in some home improvement and hardware stores. The solution of those is in many cases less than 12.5% and consequently cannot perform as well as the quality products we sell.


Advantages:

Disadvantages:

Next to gas is the cheapest chlorine available

Bulky and heavy

No dissolving required - no residue

Not stabilized-loses strength rapidly

Can be used with chemical feed pumps

High pH (10-13) raises pH of pool

"TRI-CHLOR Tablets" = Trichloroisocyanuric Acid: 3" or 1" tablets 99% available chlorine. In our store look for "Big TABS" or "Small TABS" by E-Z Clor.


Advantages:

Disadvantages:

Stabilized - chlorine doesn't dissipate

Cost slightly higher

Easy to handle

Lowers pH - pH 2.8

Low cost, low maintenance erosion feeders

Lowers total alkalinity

Highly concentrated - 99% available chlorine

May elevate cyanuric acid levels

Dissolves completely - very little residue

Not suitable for supeprchlorination


Free Chlorine Residual is the amount of chlorine in the pool which has not reacted with substances other than water. It is the chlorine which is available to disinfect pool water and oxidize organic substances. Free chlorine residual should be maintained between 1 and 3 ppm.

Shocking


Superchlorination: (also know as 'Shocking') In order to prevent buildup of contaminents a pool or spa needs to be superchlorinated periodically. The amount of chlorine needed to reach the point that will adequately burn off the contaminents will vary depending on the amount of organic material introduced by bathers and the level of free chlorine maintained in the pool. If the amount of combined chlorine is known, then the amount of new chlorine needed is ten times the amount of combined chlorine. When combined chlorine residual is not known, superchlorination is accomplished by adding 10 ppm of new chlorine to the pool. Ordinarily calcium hypochlorite (DRY CHLORINE) at a dose of at least 1 lb. per 10,000 gallons is used for superchlorination. The chart below shows the amounts of various forms of chlorine which can be used to produce 10 ppm of chlorine to the pool. Obviously using a test kit or test strips is required to know when you have achieved those levels.


Superchlorination Chart (Amount Needed to produce 10 ppm free-chlorine concentration)


Type of chlorine

GALLONS IN POOL

1,000

5,000

10,000

15,000

20,000

25,000

50,000

Liquid Chlorine

10 oz.

1 3/4 qts.

3 1/4 qts.

1 1/4 gal.

1 2/3 gal.

2 gal.

4 gal.

Tri-Chlor Tabs

2 1/4 oz.

11 oz.

1 1/3 lbs.

2 lbs.

2 2/3 lbs.

3 1/3 lbs.

6 3/4 lbs.

Dry Chlorine

2 oz.

10 oz.

1 1/4 lbs.

2 lbs.

2 1/2 lbs.

3 1/4 lbs.

6 1/2 lbs.

Non-chlorine Shock Treatments Several products have been developed which oxidize organics without the use of chlorine. We sell a couple of non-chlorine shocks which are primarily Potassium Monopersulfate or MPS for short. Pools which use those products can accomplish the reduction of organics without closing the pool for any longer than it takes to dissolve and distribute the chemicals. Those products are more expensive than chlorine but may be preferred where it is necessary to keep a pool open. The advantage with the MPS products are that you can perform an oxidation or shock cycle and in roughly 15-30 minutes later the pool or spa can be used as usual.

Chlorine Stabilizer or Conditioner

Stabilizer - Cyanuric Acid
Hypochlorous acid is a highly unstable molecule which dissipates rapidly in the presence of sunlight. This results in considerable loss of free chlorine form pools exposed to sunlight. Proper stabilization of chlorine with cyanuric acid slows the rate of chlorine dissipation without appreciably sacrificing oxidation and disinfection activity. Reaction of free chlorine with cyanuric acid produces a form of combined chlorine (chlorimide) which is active enough to aid disinfection and show up as free chlorine residual on your test kit. Proper stabilization requires 30 to 50 ppm cyanuric acid. Outdoor pools should be initially treated with 40 ppm cyanuric acid. The chart below can be used to determine the amount of cyanuric acid needed.


Establishing or Increasing Cyanuric Acid Level


CYA increase ppm

GALLONS IN POOL

1,000

5,000

10,000

15,000

20,000

25,000

50,000

10

1 1/4 oz.

6 1/2 oz.

12 3/4 oz.

1 1/4 lbs.

1 2/3 lbs.

2 lbs.

4 lbs.

20

2 1/2 oz.

12 3/4 oz.

1 3/4 lbs.

2 1/2 lbs.

3 1/3 lbs.

4 lbs.

8 1/3 lbs.

30

2 1/2 oz.

11 oz.

1 1/3 lbs.

2 lbs.

2 2/3 lbs.

3 1/3 lbs.

12 1/2 lbs.

40

3 oz.

10 oz.

1 1/4 lbs.

2 lbs.

2 1/2 lbs.

3 1/4 lbs.

16 2/3 lbs.

50

6 1/2 oz.

2 lbs.

5 1/4 lbs.

6 1/4 lbs.

8 1/3 lbs.

10 1/2 lbs.

21 lbs.

Cyanuric acid dissolves very slowly and is best predissolved in warm water before introducing into the pool. If it is not predissolved it may take several days to dissolve completely. Once added to the pool, cyanuric acid does not dissipate. It is removed from the pool only by splash out and backwash waste. Stabilized chlorine products such as trichloroisocyanuric acid will add stabilizer to the pool and may cause a gradual rise in cyanuric acid concentration. Excessive amounts of cyanuric acid can interfere with the disinfection process and at concentrations above 100 ppm may cause "chlorine lock" and clouding of the pool. Cyanuric acid level is lowered by draining part of the water out of the pool and diluting the remaining water with fresh water. Generally cyanuric acid level should be kept below 60 ppm. Stabilized forms of chlorine should not be used for superchlorination because cyanuric acid level may be increased.

Suggested Standards - Swimming Pools

 

Min

Ideal

Max

Free Chlorine, ppm

1.0

1.0-3.0

3.0

Bromine, ppm

2.0

2.0-4.0

4.0

pH

7.2

7.4-7.6

7.8

Total Alkalinity, ppm

60

80-100

180

TDS,ppm

300

1000-2000

3000

Calcium Hardness, ppm

150

200-400

500-1000+

Cyanuric Acid, ppm

10

30-50

150

 

Suggested Standards - Spas

 

Min

Ideal

Max

Free Chlorine, ppm

1.0

1.0-3.0

10.0

Bromine, ppm

2.0

2.0-4.0

10.0

pH

7.2

7.4-7.6

7.8

Total Alkalinity, ppm

60

80-100

180

TDS,ppm

300

1000-2000

3000

Calcium Hardness, ppm

150

200-400

500-1000+

Cyanuric Acid, ppm

10

30-50

150

 

Other Sanitizer Systems...

Bromine
Bromine is chemically very similar to chlorine. Bromine compounds tend to react more slowly than chlorine compounds so bromine is generally more stable and less subject dissipation in sunlight. This makes bromine active over a larger range of pH than chlorine. Bromine will combine with ammonia to form bromamines similar to chlorine but unlike chloramines, bromamines are effective bactericides and do not produce the degree of odor and eye irritation associated with chloramines. Bromine is less affected by high temperature and nitrogen wastes than chlorine so it is particularly attractive for use in hot water spas. Bromine is more expensive than chlorine and has not yet received widespread acceptance by swimming pool operators.
The form of bromine most commonly used in pools and spas is the organic chemical bromo-chloro-dimethylhydantoin which contains both bromine and chlorine. It is marketed under various trade names and is generally in tablet form for use in erosion feeders.
Bromine residual should be maintained between 2 and 4 ppm. Bromine residual is measured using your test kit to measure free chlorine. If your test kit does not include a bromine scale then bromine residual is approximately 2.25 times the reading on the chlorine scale.

Biganide disinfectants, also known by several commercially similar names. We have a product line from Leisure Time, which markets a product suite known simply as FREE which falls into this category.
This is the only disinfectant other than chlorine and bromine which has been accepted as a primary disinfectant in public swimming pools is polyhexamethylene biguanide. Biguanide is used at a concentration of 30 to 50 parts per million and a pH of 7.2 to 7.8 to kill germs and control algae growth. A special test kit is needed to test the biguanide residual. The main advantage of biguanide is the disinfectant concentration remains fairly stable so it requires less frequent adjustment than chlorine. No automatic chemical feeder is needed.
Biguanide is not an oxidizer and will not destroy organic wastes the way chlorine and bromine do. It must be used in conjunction with a peroxide shock treatment to prevent organic wastes from accumulating in pool water. Biguanide is incompatible with chlorine and most algicides. Chlorine in make-up water can cause clouding of biguanide pools. Biguanide increases the staining potential of dissolved metals in a pool so copper based algicides, copper ion generators, and pool heaters should not be used. Only chemicals recommended by the disinfectant manufacturers should be used.

Alternative disinfection options...
A variety of supplemental disinfection process equipment is being marketed for use on swimming pools. The most common are copper/silver ion generators, ozone generators, and ultraviolet light generators. These systems are becoming more and more popular. Ask the store manager about some alternative water disinfection options for your pool or spa. One product we recommend highly is PoolRX and SpaRX which are mineral sanitizers that we have tested and feel that it offers a great combination of cost effectiveness along with convenience. Mention it when you are in the store!