Model # R20841-12
Cal-Shock 65 – Fast-Acting Calcium Hypochlorite Shock
Powerful Pool Shock Treatment for Crystal Clear Water
Power Blast® Cal-Shock 65 delivers a quick chlorine boost with 68% Calcium Hypochlorite and 65% available chlorine. This fast-dissolving granular formula wipes out organic contaminants, algae, and bacteria—making it ideal for weekly maintenance or spring pool openings.
✅ Key Features
➡️ High-Strength Formula – 68% Calcium Hypochlorite, 65% available chlorine
➡️ Fast-Dissolving Granules – Works quickly to sanitize and clarify water
➡️ Effective Shock Treatment – Great for weekly use or after heavy pool traffic
➡️ Convenient 1 lb Bags – No measuring, easy to apply
➡️ Spring Start-Up Ready – Quickly restores water clarity after winter
➡️ Made in the USA – Quality and reliability you can trust
✅ Usage Tips
➡️ Balance water chemistry before application
➡️ Apply in the evening or when sunlight is minimal
➡️ Follow dosage instructions on packaging for best results
� Mobile-Friendly Dosage Guide
Weekly (Clear Water)
✅ 10,000 gal – 1 lb
✅ 20,000 gal – 2 lbs
✅ 25,000 gal – 2.5 lbs
✅ 30,000 gal – 3 lbs
✅ 35,000 gal – 3.5 lbs
✅ 40,000 gal – 4 lbs
Green Water Treatment
✅ 10,000 gal – 2 lbs
✅ 20,000 gal – 4 lbs
✅ 25,000 gal – 5 lbs
✅ 30,000 gal – 6 lbs
✅ 35,000 gal – 7 lbs
✅ 40,000 gal – 8 lbs
⚠️ Important: Always follow manufacturer’s directions on the product container. Store unopened bags in a cool, dry location.
➡️ Shock your pool back to crystal clarity with Cal-Shock 65.
Order today for fast shipping and dependable water care.
For More Pool Chemicals
I'm looking for pool shock to sanitize my drinking water. Will this work?
Reply
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.
Reply
I tested my chlorine levels and they were at 0, so I shocked it. This didn't bring the levels up at all. What could be the problem and what should I do?
Reply
If your chlorine level remained at 0 after shocking, I would recommend checking the pH, alkalinity and cyanuric acid levels. I would also recommend checking the available chlorine percentage on the pool shock.
Reply
I have an in ground vinyl swimming pool and usually use liquid shock. I have heard that the granular shock is better but it's not for vinyl pools. Is there another type of shock that I can use that is stronger than the liquid?
Reply
You can use the granular shock but I would recommend adding it to a bucket of pool water to pre-dissolve it then pouring it along the perimeter of the pool.
Reply
My pool company uses liquid shock in my pool. Is this granular shock any better?
Reply
Yes. If you look at the labels of both products, you will find that liquid shock is weaker. The bottle has vented caps (to vent chlorine gas) so the longer it sits on a shelf, the weaker it gets. Granular shock is a lot stronger and does not lose its strength as long as it's stored properly.
Reply
Why do I need to shock the pool if I use chlorine tablets?
Reply
Chlorine tablets alone are not enough to keep the water sanitized. Pool shock helps to oxidize the water as well as breakdown chloramines.
Reply
$39.99
$109.97
$19.63
$38.10
$280.71
The Most Helpful Review
5 0
(5 out of 5 stars)
Reviewed By: KENNETH C. from Port Isabel Texas ()
as clear as the pool ever was!
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The Most Recent Reviews
2 0
(4 out of 5 stars)
Reviewed By: K. K. C. from Orient, IA ()
Excellent product. Higher active ingredient percentage than you can get at local stores.
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2 0
(4 out of 5 stars) Great Pool Chlorine treatment
Reviewed By: John T. from Erin, TN ()
Pros: Good strength and reasonable price.
Cons: None
This is a great chlorine treatment. It is stronger than the shock that is available locally. I can use less and still maintain my pool.
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5 0
(5 out of 5 stars) Bought for Emergency Water Purification - Hope I never have to use it!
Reviewed By: Pool Shockin' Daddy from Boise, ID ()
Pros: Convenient 1 lb bags, shipped quickly, arrived in good shape
Cons: None. I would purchase from Inyo Pools again, if I had it to do it all over.
I ordered the Zappit 68% Calcium Hypochlorite to serve as an emergency source of water purification in the unlikely event of a disaster or disruption in clean, potable water in my area. Since this product, made by PPG, is NSF certified for purification of public drinking water, and since the practice is approved by the EPA, I thought it wise to stock up. In hindsight, 12 pounds was a bit excessive, and I have since given away several bags. Since Inyo Pools can't recommend this product for use beyond its stated purpose, they won't really provide instructions for use as a means of emergency drinking water purification. Consequently, if you choose to purchase this, or similar CalHypo products for that purpose, do your homework, and make sure to research (the EPA website should be your first stop) and know the EXACT amount to add to water to safely purify it. It would also be wise to print off several copies of these instructions, and keep them with the product, so when the time comes to use it, you're not relying on memory or guesswork to safely purify your drinking water. Also, remember that since Zappit and similar CalHypo products are highly corrosive, be sure to store the product safely.
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1 0
(5 out of 5 stars) Great Product!
Reviewed By: Robert B. from Medford, OR ()
This product is really the best I've found for 100% Hypochlorite. I am always please with products I get from inyopools.com. I recommend this product and inyopools.com to my family and friends.
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1 0
(5 out of 5 stars) Cal Shock 65
Reviewed By: Robert M. from Stafford, VA ()
Pros: Quick shipping and easy to deal as a pool owner.
Cons: None to date.
We have been ordering from Inyopools for over 1 year. We have been happy with this shock for our inground 25K galllon pool. It dissolves well and has not bleached our liner.
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(5 out of 5 stars) Chlorine
Reviewed By: Janice D. from Hillsboro, MO ()
When the product arrived it was well packed and arrived just a few days after I ordered. I am very pleased with this product and you company.
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(4 out of 5 stars) shock
Reviewed By: tripp from Woodstock, GA ()
Good Shock. Nice that it arrived at the door quickly.
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