What is Liquid Chlorine for Pools?
Sodium Hypochlorite is commonly called liquid chlorine or bleach. Most household bleach that you will find in stores is 6% chlorine. Pool chlorinating liquids may be 10% or 12.5% chlorine.
If you buy household bleach, you want pure liquid chlorine with no additives. Additives such as fragrances, thickeners (splashless), or surfactants (outdoor bleach) may cause foaming. Bleach with fabric protectors (chloromax technology) may also cause foaming.
Most Clorox bleach today says it has Cloromax Technology. They are polymers that create foaming and are not suitable for pools. Clorox Germicidal Bleach did not have additives but the December 2019 label on their website now shows Cloromax Technology. So look carefully at the label and ingredients on any Clorox bleach products you intend to use in your pool.
Most retail bleach is manufactured by a few chemical suppliers. KIK corp is probably the biggest. They all use the "ChloroMax" technology that Clorox patented and then licensed out. So even the store brands like Target or Walmart will say their bleach is regular unscented, etc and somewhere on the bottle will be the phrase "Fabric Protection Technology" (or some combination of words like that).[1] Read bleach labels carefully and look for code words that may imply it has additives other then chlorine.
Check the date code on any liquid chlorine. You want fresh chlorine preferably bottled within the last 3 months. Liquid chlorine strength breaks down with time and temperature.
Don’t buy liquid chlorine if its stored outside in the garden center. The heat and sun weakens the chlorine.
All bleach and liquid chlorine is a mixture sodium hypochlorite, sodium chloride, sodium hydroxide (lye) and water. The sodium chloride and lye come from the manufacturing process, there is no way to get rid of it and the lye is needed to raise the pH of the end product so that the sodium hypochlorite remains stable during its shelf life.
Liquid Chlorine vs Tablets
Liquid chlorine is the purest form of chlorine you can add to your pool. Residential pools cannot add pure chlorine since chlorine is a gas. To transport the chlorine it needs to be bound to other stuff. The chlorine gas in liquid chlorine is bound to water with some salt and lye added for the manufacturing process. The salt will accumulate in your pool water and is harmless in small quantities.
To manufacture solid tablets chlorine gas is bound to other solid chemicals whose accumulation in pool water may not be desirable. Trichlor tablets have chlorine bound to CYA and dry acid. Dichlor tablets have chlorine bound to calcium. Both CYA and calcium accumulate in the water and can only be eliminated by draining.
CYA levels over 80 can reduce the effectiveness of chlorine and require higher free chlorine levels to be maintained for adequate sanitation.
High calcium levels can cause scale on pool surfaces and in a Salt Water Chlorine Generator.
How Much Liquid Chlorine Should You Buy and Use
When using liquid chlorine you need to calculate how much liquid chlorine poured into your size pool will give you the desired amount of Free Chlorine as measures in Parts Per Million (PPM). This takes some calculating and we have a free app called Pool Math to do these calculations for you.
The strength of liquid chlorine depends on where you buy it and it's intended use. Household bleach can be found with chlorine strengths from 4% to 6%. Pool Chlorinating liquid sometimes called "Liquid Pool Shock" can be found in strengths from 10% to 12%. The label on the jug will tell you the % of Sodium Hypochlorite.
If you need to get an estimate of the amount of water in your pool you can use the calculator at the bottom of the old Pool math web page. You simply enter the pool dimensions and average depth and it gives you the gallons of water in the pool.
Pentair has a Pool Volume Calculator that lets you select from rectangular, oblong, round, and triangle shapes.
Finally, you need to estimate your daily chlorine consumption. An average pool in the summer in full sun will consume 3 to 4 ppm of chlorine from the suns UV rays. In the Spring and Fall chlorine consumption will decrease due to the lower sun angle.
If you are unsure, then begin with adding 3 to 5 ppm of liquid chlorine daily as calculated by Pool Math. Your pump should be running when adding any chemicals and let your pump run for at least 30 minutes after adding the liquid chlorine.
Then test your Free Chlorine daily using your pool test kit. If your free chlorine is increasing above your target then reduce the daily quantity of liquid chlorine added. If your free chlorine is decreasing then increase the daily quantity of liquid chlorine added. Within a few days you will know your pools daily chlorine usage and how much liquid chlorine is required.
For example, with a 10,000 gallon pool, adding 40 ounces of 10% liquid chlorine will raise the free chlorine by 3.1 ppm. If 5% liquid chlorine is used it will require 70 ounces of liquid chlorine to add 3 ppm of free chlorine.
Our Recommended Levels page will help you determine the correct Free Chlorine and other pool water chemistry levels for your pool.
Confused? Need Help? Not sure what to do? Start a thread on the Just Getting Started section of the TFP Forum and we will help you.
Where to Buy Liquid Chlorine
Liquid chlorine can be found in many different types of stores:
- Supermarkets have liquid chlorine as bleach.
- Hardware stores sell liquid chlorine as cleaners
- Pool stores and "Big Box" stores sell liquid chlorine as "Liquid Pool Shock" or "Pool Chlorinating Liquid"
- Industrial chlorine suppliers will sell refillable jugs of chlorine
- Farm & feed stores, Dollar General, cleaning supply warehouses all have some form of liquid chlorine,
Liquid Chlorine Tracker Map
The Liquid Chlorine Tracker Map is a work in process that allows members to report where they find Liquid Chlorine available and to search by zip code to find sources in your area.
Give it a try and contribute locations of sources of Liquid Chlorine you find.
You can also check the latest entries in the Best Places to Buy Liquid Chlorine thread.
USA
Check your local pool stores for 10% or 12% “liquid shock” or “chlorinating liquid”. They are usually not the least cost but can be available and convenient.
Use their websites to check for availability in stores around you:
- Home Depot - HDX 128oz Chlorinating Liquid 3 Pack or HDX 121 oz. Germicidal Bleach which will likely be 8.25% and located near the cleaning products
- Wal-Mart - Pool Essentials Chlorinating Liquid 2 Pack
- Lowes - Kem-Tek
- Ace Hardware - should have 10% bleach
- Ollies Bargain Outlet
- Menards
- Rural King
- Fleet Farm - Swim Shock Liquid Pool Chlorinator - 4 Pk
- check any of your local stores to see who carries liquid chlorine-janitorial services might offer liquid chlorine if you have your own containers
Canada
- Canadian Tire normally carries liquid chlorine
- Wal-Mart
Unable to Find Bleach/Liquid Chlorine
Read Unable to Find Bleach for other options if you cannot find any sources for Liquid Chlorine.
