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Model # R20841-6

Alternate Part #'s LZA71428A

Product Description

Cal-Shock 65 – Fast-Acting Calcium Hypochlorite Shock

Powerful Pool Shock Treatment for Crystal Clear Water

Power Blast Cal-Shock 65 delivers a quick and effective chlorine boost with 68% Calcium Hypochlorite and 65% available chlorine. This fast-dissolving granular formula is perfect for destroying organic contaminants, algae, and bacteria, making it a top choice for weekly maintenance or spring pool openings.

Key Features:

  • High-Strength Formula – 68% Calcium Hypochlorite, 65% available chlorine

  • Fast-Dissolving Granules – Acts quickly to sanitize and clarify water

  • Effective Shock Treatment – Great for weekly maintenance or heavy pool usage

  • 1 lb Convenient Bags – Easy to use, no measuring needed

  • Ideal for Spring Start-Ups – Quickly restores water clarity after winter

  • Made in the USA – Quality and reliability you can trust

Usage Tips:

  • Ensure water is properly balanced before application

  • Apply in the evening or when sunlight is minimal

  • Follow dosage instructions on container for optimal results

Compares to BioGuard® Burn Out

Restore sparkle and hygiene to your pool fast with Cal-Shock 65—your go-to solution for reliable and affordable water care.

Product Specifications

# of 1 lb Bags:
6
Type:
Chlorine Shock
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?     Asked on 1/25/2012by Guest

I'm looking for pool shock to sanitize my drinking water. Will this work?
 Reply

A  Answered on 1/25/2012 by InyoPools Product Specialist Patrick P.

I have heard of people using pool shock to sanitize drinking water but I can not promote the use of any pool shock for this purpose. You will want to contact the NSF for further information.
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?     Asked on 5/27/2012by Guest

My water is turning green. I had my water tested and it shows 5 on the total chlorine and 0 on the free chlorine, what can I do?
 Reply

A  Answered on 5/27/2012 by InyoPools Product Specialist Patrick P.

  Chlorine in water may be present in two forms, free and combined. Free chlorine does the hard work of killing bacteria and oxidizing contaminants. When you add chlorine to water, you are actually adding free chlorine. When the free chlorine combines with contaminants, it becomes combined chlorine, or chloramines. This form of chlorine has very little sanitizing ability, and no oxidizing ability. Total chlorine is just the sum of both combined chlorine and free chlorine. You may have what is considered chlorine lock. Chlorine lock can occur in swimming pools where the chlorine in the pool is rendered inactive, even though you may have a total chlorine reading in the pool. In essence, a chlorine “block” means that the chlorine in the pool is literally being blocked from doing its job by other chemicals. The quickest way to resolve a chlorine lock issue is to partially drain and refill the pool.
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?     Asked on 10/12/2012by Guest

Can I add shock through my automatic chlorinator?
 Reply

A  Answered on 10/12/2012 by InyoPools Product Specialist Patrick P.

No, you should never add shock through an automatic chlorinator. Never mix different types of chlorine. Pool shock can be added to a bucket of water and poured directly into the swimming pool.
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?     Asked on 10/18/2012by Guest

I have an in ground pool with a mesh winter cover. Several weeks ago, I had added 2 gallons of chlorine to the pool. Since then, with the mesh cover still on, the water has turned green. I've been adding about a gallon of shock each week without improvement. Should I continue adding shock to the pool or should I wait?
 Reply

A  Answered on 10/18/2012 by InyoPools Product Specialist Patrick P.

I would recommend waiting until the pump and filter are running again before adding any more shock to the pool. Algae needs two things to grow: food and light. With a mesh winter cover, the algae has more than enough light to grow regardless of the shock that you're putting in. Also, shocking the pool without circulation can cause bleaching of the pool surface
 Reply


?     Asked on 10/18/2012by Guest

My pool company recommends using a phosphate remover. Do you have any such item?
 Reply

A  Answered on 10/18/2012 by InyoPools Product Specialist Patrick P.

I would recommend using  Phosfree. The product container has easy to follow directions and will help you eliminate your phosphate problem.
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