Pool Disinfectants: An Introduction

The first thing you need to do before buying any chemicals is figure out how many gallons your swimming pool is. This figure will make it easier for you to get the right size of whatever disinfecting or sanitizing product you are going to buy from the pool supplies store. If you don’t remember the total gallonage, you can usually find it on any paperwork you received when the pool was first built. If not, you can also figure out how many gallons the pool holds by doing some simple math. If you have a rectangular shaped pool, you can simply multiply the width, length and depth together and multiply the product by 7.5. If you have a more round shaped pool multiply the depth by the diameter and multiply the answer by 5.9.    

One last thing you should do before purchasing chemicals is to test the pool water to measure the pH. You probably won’t need to apply any chemicals right away if the pH measures somewhere between 7.6 and 7.2. If the number is higher or lower, that is what will determine which product you should buy at the supply store. While testing the water you should also make note of any other characteristics of the water like green or yellow tinge, floating algae or a slimy feel to the water. Be sure to tell the supply store salesperson about any of these things as they can help you decide which type of product will work best.

Although iodine was mentioned as one of the commonly used disinfecting products, it should not be applied by yourself. Professional pool maintenance techs should be the only ones applying iodine to a swimming pool because it is highly corrosive and has the potential to severely damage the skin and eyes during the application or after it. If not applied correctly it can also cause a discoloration of pool water and/or lining and can also damage pool equipment like the filtration system.  Iodine should also only be chosen as a disinfectant if no other methods have been successful.

A much more common product that is used for sanitizing or disinfecting is Bromine. This product generally comes in the form of a powder. This powder can also sometimes be sold in the form of a stick or pellet. The way bromine works is that it creates an acid when it hits the water. This acid, hypobromous acid, reacts differently depending on the pH level of the water it is being used in. If the water has a pH higher than 7.6, then the hypobromous acid is less effective. 

Probably the most commonly used product for sanitizing or disinfecting is chlorine. Everyone has heard of chlorine. Two reasons why it is probably so popular is that it is the cheapest and it has the same effectiveness no matter what the pH level is. It also comes in a wide variety of forms including powder, tablets, granules, sticks or liquid. Of course, like any product there are some cons of using chlorine as well. Sometimes the use of chlorine can cause irritation of the skin and eyes if there is too much of it in the water. 

Another factor to consider when deciding between chlorine and bromine is amount of direct sunlight the pool gets. This is because chlorine does not lose effectiveness in lots of direct sunlight, where bromine does. Another reason many people choose chlorine over bromine is that if the pool is in direct sunlight, chlorine will be just as effective as bromine becomes less effective.

So, if you are a new pool owner, it would greatly benefit you to ask the pool supply store clerk or salesperson their advice on products. They not only have experience and are up to date on the latest treatments, but they also are familiar with your local environmental factors that can affect pool care.