Swimming Pool Blog

The Many Types of Pool Shock

The Many Types of Pool Shock
by Rob Cox  February 13, 2013

Pool Shocks of Many Types

cal hypo

Calcium Hypochlorite, or Cal Hypo for short, has been the most popular form of pool shock treatment.

Sodium Hypochlorite, popular with service companies and sunbelt pool owners,  was the alternative to using powdered or granular pool shock.

But Cal Hypo, and Liquid chlorine - as popular as they have been, do have certain disadvantages.




The Problem with Cal Hypo

Cal Hypo is a great all purpose shock, don't get me wrong! It's cheap and abundant, and works fast as a disinfectant and sanitizer. But, it does have a few drawbacks.

  1. Should be diluted to prevent damage to all pool surface types.
  2. Adds calcium to your pool; a problem for already hard pool water.
  3. Leaves behind a messy "shock dust" after a pool shock treatment.
  4. 65% available chlorine. Not bad, but some pool shocks are stronger.
  5. No Swimming for 12-24 hours after treatment, and covers should be open
  6. Cal Hypo is a volatile, hazardous chemical. Some pool shocks; not so much.

The Problem with Liquid Chlorine

Liquid chlorine, or bleach, as us pool guys call it, is a 12.5% strength, as opposed to household bleach, which is a 5% strength liquid chlorine. It burns clean with no shock dust, and distributes itself fast through the pool. But, using liquid chlorine as a pool shock treatment also has a few disadvantages.
  1. Difficult to obtain in many parts of the country.
  2. Online retailers are prohibited from shipping liquid chlorine shock.
  3. Hazardous for consumers to transport and store safely.
  4. Liquid pool shock will easily bleach your clothing.
  5. Very High pH level may affect pool pH.
Necessity is the mother of invention. Nowadays, the store shelf has widened and we now have 10 types of granular pool shock. Each has their own specific benefits or advantages. Created by chemical engineers to improve solubility, speed of kill, or to add in other features such as clarifiers or stabilizers.

The Best Pool Shock

What is the best pool shock to use? "It depends" is the short answer, and what it depends on is described below. This blog post aims to help you figure out which pool shock is best for your pool type or situation.


  • Non-Chlorine formula is safer to store.
  • Chlorine Free pool shock won't bleach liners.
  • No Pre-dissolving required.
  • Swim instantly after shocking.


  • 73% available chlorine pool shock
  • Nearly 50% more powerful than HTH Super Shock
  • pH balanced for neglible effect on your pool pH
  • The most powerful shock allowed by law!


  • Lithium shock won't contribute to hardness levels.
  • Preferred for it's gentle treatment of vinyl liners.
  • No Pre-dissolving, it's a very fine shock.
  • Swim instantly after shocking.


  • Several water treatments in one
  • Adds the power of Borates to your pool
  • Stabilizes alkalinity, buffers pH
  • Clarifies water with shine and sparkle


  • Oxidizer and Clarifier pool shock treatment.
  • Uses the power of Oxygen to disinfect.
  • Stays active for up to 10 days in your pool.
  • Compatible with Biguanide pool sanitizers.


  • Granular pool shock in a bucket.
  • Stabilized formula is protected from the sun.
  • 99% Sodium Dichloro-S-Triazinetrione.
  • Fast dissolving, pH neutral.