Increasing Chlorine Formulas

Proper water chemistry is crucial to the safety and health of the public who use public water facilities.  The following information regarding increasing chlorine should be helpful in maintaining the quality of the water in swimming pools, spas, hot tubs and wading pools in Clark County.  This information is also available for download in Adobe PDF format.   Information on decreasing chlorine is also available.

 


Instructions

STEP 1:  Determine the free available chlorine (FAC) in the pool water (ppm).  Using the DPD test kit, following the test kit instructions

STEP 2:   Determine the amount to increase the chlorine to (ppm)

STEP 3:   Determine the ppm change using the following to increase:
          Desired ppm - Current ppm (FAC) = ppm change
          Example:  Desired ppm (20) - Current ppm or FAC (1.0) = 19 ppm change

STEP 4:   Identify the chlorine compound to be used to increase the chlorine level, plug in the amount to increase the chlorine, and use the following formulas:
 

  • Make sure the pH is within the acceptable range of 7.2-7.8. These chlorine compounds will signifigantly change the pH and affect the effectiveness of the chlorine.

  • You must know the volume of water the pool holds.

1. Calcium Hypochlorite  .125 x ppm change x pool volume/10,000 = pounds
          pH 11.8, granular and tablets
2. Sodium Hypochlorite  .1016 x ppm change x pool volume/10,000 = pounds
          pH 13.0, liquid
3. Lithium Hypochlorite  .250 x ppm change x pool volume/10,000 = pounds
          pH 10.7, powder
4. Chlorine Gas  .08125 x ppm change x pool volume/10,000 = pounds
          pH <1.0, gas

note: " / " means divided by,  x means multiply

EXAMPLE:

The free available chlorine (FAC) is 1.0.  The operator has decided to raise the chlorine to 20ppm and keep the pool closed for 8 hours to satisfy the "9600 rule" and will use Calcium Hypochlorite.  Volume of the pool is 200,000 gallons.

20 ppm (chlorine level to be reached) - 1.0 ppm (FAC present)= 19ppm change

.125 x 19 x 200,000/10,000 = 47.5 pounds of Calcium Hypochlorite that must be added to the pool.

How To Shock a Pool

The "smell of chlorine" in a pool is actually the smell of chloramines, the chemical compounds formed when chlorine combines with sweat, oils, urine and other contaminants in the water. Chloramines are not effective in disinfecting the water and cause eye and skin irritation.  Breakpoint Superchlorination or "Pool Shocking" is required to combat the loss of effective chlorine in the water.  Breakpoint Superchlorination is required (on average) every 2-3 weeks for indoor pools and every 7-10 days for outdoor pools.  Heavy bather loads will increase the need for Breakpoint Superchlorination.

Instructions for Breakpoint Superchlorination of your water are available to read online, or you can download and print a copy of the instructions in Adobe PDF format.

Public Water Facility Chemical Log Sheets

Public water facilities are required by 410 IAC-6-2 to keep a record of the pool water chemistry.  Log Sheets for recording this information are available for download in Adobe PDF format.

 

 

Pool Safety Homepage     Pool Accidents and Injuries     Pool Chemistry     Pool Chlorination     Pool Inspections     Pool De-chlorination
Pool Fecal Accidents     Pool Inspections     Pool Regulations     Pool Shocking Instructions     Pool 9600 Rule
 

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