Dichlor Shock vs. Cal Hypo Shock

When it comes to shocking your pool there are a variety of options available for use. The most common are Sodium Dichlor (Dichlor) Shock (Dichlor) and Calcium Hypochlorite (Cal Hypo) Shock. So what exactly are the differences between the two? We're glad you asked.

In the article below we will cover the basics of these two pool shocks, detailing when and why to use each one.

Highlights include:

Pool and Spa/Hot Tub
Dichlor Shock is designed for saltwater pools or hot tubs/spas; Cal Hypo Shock is not.

White Powder and Gray Powder
Dichlor Shock is typically white in color; Cal Hypo is typically white or gray in color.

Cyanuric Acid
Dichlor Shock contains about 10% Cyanuric Acid, which protects the chlorine in the product.

Calcium Iron
Cal Hypo Shock contains calcium, which allows it to be used as a maintenance or treatment product.

Dichlor Shock

Sodium Dichlor is a sodium-based chlorinated granular shock that is designed to be used in a saltwater or spa environment. The sodium base allows it to dissolve quickly and clearly, leaving no turbidity or cloud to the water. Dichlor can be used in all interior types — vinyl, plaster, pebble tech, and painted finishes. Dichlor can be used as a maintenance or treatment product.

Dichlor, which has a pH of 6-7 at 25°C (1% solution), is typically white in color and has a slight chlorine odor. Dichlor is stabilized and contains approximately 10% Cyanuric Acid. Cyanuric Acid is used to protect the chlorine in the product from the harmful effects of the sun's UVA and UVB rays.

To add a Dichlor shock — such as Leslie's Chlor Brite — to your pool or spa, simply measure out the amount needed per the volume of water and Parts Per Million (ppm) lift needed. Then sprinkle it around the perimeter of the pool or spa with the main circulation system running. (It is not suggested or recommended to pre-dilute this product before adding.)

Leslie’s Proprietary Chemicals

Available Chlorine Active Ingredient Appearance pH CYA Super Chlorination
Sodium Dichlor 56% 99% White Granular 6 - 7 Approx 10% 21 oz per 10,000 gallons
Calcium Hypochlorite 70% 73% White/Gray Granular 10.4 - 10.8 N/A 18 oz per 10,000 gallons

Cal Hypo Shock

Calcium Hypochlorite (Cal Hypo) is a calcium-based granular chlorinated shock that can be used as a maintenance or treatment product. Cal Hypo has the highest percentage of available chlorine and is extremely effective at eliminating algae.

Because Cal Hypo contains calcium, it is not recommended for use in saltwater applications, and although it does dissolve quickly, it does take longer to dissolve than Dichlor. Cal Hypo is not recommended for painted, vinyl, fiberglass and pebble tec interiors because it can possibly bleach the color of the surface. Depending on the calcium hardness and total dissolved solid levels in the water, adding Cal Hypo can cause some turbidity and clouding to the water.

Cal Hypo is white/gray in color, has a slight chlorine odor, and a a pH of 10.4-10.8 @ 77 °F (25 °C). Cal-Hypo is not stabilized as it does not contain any Cyanuric Acid (CYA).

Leslie’s Proprietary Chemicals

Cal Hypo Active Ingredient Available Chlorine% Granular Size
Power Powder Plus 73% 70% Fine
Power Powder Pro 73% 70% Medium
Power Powder Granular 70% 68% Course

To add Cal Hypo Shock — such as Leslie’s Power Powder Plus — to your pool, simply measure out the amount needed per the volume of water and ppm lift needed. Then sprinkle it around the perimeter of the pool with the main circulation system running. (It is not suggested or recommended to pre-dilute this product before adding.)


Hopefully you now have a better idea of which shock is better-suited to for your pool or hot tub/spa.

If you have any other questions, we’re here to help. Stop by or contact your local Leslie's store or call us at 1-800-537-5437 for expert assistance.