Superchlorination is the application of extremely high levels of chlorine for the purpose of “shock treatment” of the pool water (usually 10 mg/l of free chlorine).
Why Should Pool Water Be SuperChlorinated?
1. To kill bacteria, algae, etc.
2. To improve water clarity.
3. To chemically destroy chloromines (combined chlorine). Chloromines are undesired because they have a strong chlorine odor and cause eye irritation problems.
How Often Should Pool Water Be SuperChlorinated?
1. Heavy pool usage- once per week
2. Light pool usage- once every two weeks
3. Whenever the combined chlorine residual is above 3.0 milligrams/liter (mg/l)
What Chemicals Are Used To Increase the Chlorine Residual?
1. Calcium Hypochlorite (HTH)
Add 2 oz. per 10,000 gallons = 1 mg/ of chlorine
2. Sodium Hypochlorite
Add 1 cup per 10,000 gallons = 1 mg/l of chlorine
3. Sodium Hypochlorite (5 1/4%, Hilex)
Add 1 gallon per 50,000 gallons water = 1 mg/l of chlorine OR
Add 1/3 cup per 1,000 gallons water = 1 mg/l of chlorine
4. Gas Chlorine
Add 1/3 oz. per 10,000 gallons water = 1 mg/l of chlorine
How is Chlorine Added to the Pool
1. HTH- dissolve in water- (CAUTION: Add HTH to the water, NEVER water to chemical). Pour resulting liquid around the perimeter of pool. Discard any undissolved material.
2. Sodium Hypochlorite- pour around perimeter of pool
3. Gas chlorine- increase rate of chlorine feed
NOTE: Clearly post the pool closed for use during superchlorination; lock entry doors, etc.
How Long Is the Pool Superchlorinated?
1. At least overnight
2. Longer if possible
When Can the Pool Be Used Again?
After the free chlorine has dropped below 3 mg/l
How Can the Chlorine Residual Be Lowered?
1. Time- wait for the chlorine residual to drop (this is the preferred method)
2. Add sodium thiosulfate (or equal) to neutralize the chlorine
Outdoor Pools:
If chlorine stabilizer is used and a chlorine residual of 3-5 mg/l is maintained, the need of superchlorination is greatly reduced.