Chlorine for Pools | Test Your Own Pool

Pool maintenance has one ultimate goal: keep the water clean and clear of any organics to make it a safe swimming experience. Pool chlorine will be your best friend in this endeavor.

Adding chlorine to your pool can solve and prevent many pool water issues you may encounter. Let’s break down the use of chlorine for your pool and how it affects overall pool chemistry

Chlorine is a Sanitizer For Pools

Swimming pools left unchecked for even a short period can quickly become a cloudy habitat for bacteria and organic contaminants like algae. You need a sanitizer to ensure this doesn’t happen.

Chlorine is the most popular sanitizer for pools due to its widespread use, lower price, and availability. Bromine and biguanide are other forms of sanitizers.

Not only does chlorine target and kill microorganisms in pool water, but it also carries an extra function as an oxidizer that burns up organic contaminants introduced into the water by nature (leaves, pollen, dirt) or swimmers (lotion, body oils, sweat).

Quite simply, pool chlorine acts as a fixer and as a preventer.

Different Types of Pool Chlorine

One of the reasons why chlorine is the most popular sanitizer is the wide availability of the chemical. Chlorine can come in many types: liquid, gas, powder, and tablets. The main difference between the variations is whether they are stabilized or unstabilized.

Stabilized Chlorine

Stabilized chlorine, aptly named, contains a stabilizer like cyanuric acid (CYA). The stabilizer creates a compound that does not break down in sunlight so the chlorine will last longer in the pool. It allows you to change the chlorine less frequently in the pool.

However, too much CYA in the water can inhibit chlorine’s ability to sanitize and oxidize, so make sure your CYA levels are checked before using stabilized chlorine.

Most Common Stabilized Chlorine: Trichlor and Dichlor

Unstabilized Chlorine

Unstabilized chlorine is essentially just chlorine with no stabilizer added. This means unstabilized chlorine will break down in UV rays faster, forcing you to add chlorine more frequently.

This reinforces the importance of having balanced water and enough stabilizer to control chlorine use.

Most Common Unstabilized Chlorine: Liquid chlorine, Lithium Hypochlorite, and cal hypo

What Chemical Levels Are Affected By Chlorine?

Since chlorine is the cornerstone of cleanliness, it naturally affects pool chemistry.

Whether using test strips or a liquid test kit to check water levels, chlorine has some affecting relationship with

Free Chlorine (FC): The overall level of sanitation in the water that kills all the germs, algae, and other contaminants that may be living.
Combined Chlorine (CC): The reaction of free chlorine binding with organic contaminants and ammonia in the water during sanitation. Also known as chloramines.
CYA: Chlorine stabilizer that protects it from UV rays making it last longer in the water.

Chlorine Demand and Chlorine Lock

Naturally, algae and other organic materials consume the chlorine added to the pool. This consumption is known as chlorine demand, defined as the “amount of chlorine that will react with contaminants before any chlorine is left unreacted.” The more crap in the water, the more chlorine is needed.

There are some misconceptions about chlorine not working, no matter how much is put in the pool. This is commonly called chlorine lock; your chlorine levels will not increase even when more has been added. By and large, chlorine lock isn’t a real thing.

However, when CYA levels are too high, the amount of chlorine added might not be enough. So it isn’t “locked”; there isn’t enough chlorine in your pool.

Bottom Line

While other sanitizers can be used, chlorine is the easiest and most affordable choice. Just remember, any sanitizer is only as effective as your water testing!