Chlorine Products

The objective of all chlorine products is to release free chlorine into the water.  Free Chlorine stays in solution and is ready to combine with waste material to quickly render it harmless.  There are several different products on the market with various names and claims.  However, once they are in solution the sanitizing characteristics and chemistry is similar.

The type of chlorine you use depends on personal preference, availability, climate, water quality, storage, handling and cost.  Chlorine use falls into 2 basic categories; 

Daily Use Chlorine:  This is Chlorine that is used to maintain the normal chlorine levels.  This chlorine MUST be added EVERY day to maintain the Perfect Chlorine Range of your pool.  (See Free Chlorine)  This type of chlorine is normally added slowly by an automatic chlorinator or floating chlorinator.  Automatic Chlorinators are designed to release a constant amount of free chlorine every day.  However, since the dissolve rate varies with circulation, heat, valve expansion and many other factors; MOST AUTOMATIC CHLORINATORS DO NOT WORK VERY WELL.  For this reason, you MUST test the chlorine daily to monitor whether your chlorinator is working properly.  Daily use chlorine is typically a slow dissolving solid such as tablets or sticks.

Shock Chlorine:  This Chlorine is used for periodic shocking, super chlorination, algae killing or for small additions required when the automatic chlorinator is not working properly.  Shock Chlorine is typically a liquid or a fast dissolving solid.  You want this type of chlorine to dissolve and disperse immediately so that the chlorine gets up to the desired level quickly and so that the bottom of the pool is not stained.

Independent of it's use, chlorine is either Stabilized or Un-Stabilized.  Stabilizer is added to chlorine to insure a steady flow of stabilizer into the water proportional to the chlorine consumption.  Stabilizer is used in outdoor pools because it reduces the neutralizing effect that sunlight has on free chlorine.  The active chemical in stabilizer is Cyanuric Acid or CYA for short.

Here are the Main Chlorine Types for Residential Use:

Chlorine Type Characteristic Available Chlorine (Typical) Stabilizer Included pH May Cause Build Up Of: Advantage Disadvantage
Sodium HypoChlorite Liquid 10% No 13 Sodium or TDS Easy for Shocking, inexpensive, low residue 90% water so difficult to handle, loses strength in storage, increases acid demand
Calcium HypoChlorite Solid Granules 65% No 11 Calcium Will stain surfaces, so it must be premixed. Calcium may be an advantage if your water is low in calcium.  Convenient, compact.  Stores well May be a problem if your water is high in calcium, increases acid demand, creates cloudiness temporarily.
Fast Dissolving Calcium HypoChlorite * Fast Dissolving Granules 75% No 11 Calcium Fast Dissolving.  Won't stain Very Expensive compared to normal calcium hypochlorite.
Lithium HypoChlorite Solid Granules 35% No 10 Lithium or TDS Completely soluble.  No premixing.  Dissolves fast. Expensive.  High residual.
TriChlor Solid Granules, Sticks or Tablets 90% Yes, 54% 2.8 Stabilizer Slow dissolving, great for chlorinators. Low pH increases base demand and reduces total alkalinity.
DiChlor Solid  Granules 59% Yes, 57% 6.7 Sodium, TDS or Stabilizer Little effect on pH More expensive than TriChlor.  More residual.
Chlorine Gas Pressure Liquefied Gas 100% No 1 Nothing Pure Chlorine, No build up, inexpensive Very dangerous, not practical for residential use due to equipment required and transport of tanks.

* These are specially manufactured granules for fast dissolving.  The most popular brand is Super Sock It® by HTH (this is not a commercial for them.  It's listed here because it's unique)

I personally use TriChlor in my automatic chlorinator for daily chlorine.  I use Calcium Hypochlorite granules dissolved in a bucket of warm water for shocking, etc.  I store these outside.  I only have to buy them once a year because they store so well.


Perfect Pool and Spa Software! Users: Go to the setup screen and click on the product that you will be using.


Copyright © 2001, All rights reserved