The Most Important Thing all DIY Pool Owners Must Know!

What is the Most Important Thing All DIY Pool Owners Must Know?

Owning a pool is all about family fun, pool parties, nighttime swims, and improving your backyard landscape… until it isn’t so much fun anymore. Owning a pool also comes with the responsibility of routine maintenance. The key to a clear, safe, and healthy pool is understanding your pool’s chlorine needs. Why? Because the type of chlorine product you use is crucial in ensuring your pool remains a sparkling oasis rather than a murky pond. I’ve come across pools that look great, but the water chemistry is damaging the surface and equipment. Even a clear pool can be deceiving.

It is also important to know the pros and cons of the chlorine you just pulled off the shelf at your local pool supply store. Not all types of chlorine are the same and each type of chlorine leaves behind byproducts that can cause problems down the road. Just because it’s on sale at Costco doesn’t mean its ok to use in your pool.

Why is Chlorine So Important?

Chlorine is the superhero of pool maintenance. It sanitizes your pool by killing bacteria, algae, and other unwanted organisms, and ensures the water is clean and safe for swimming. Without chlorine, your pool could become a breeding ground for harmful pathogens. And no, you can’t run a crystal clear and safe swimming pool without it.

However, not all chlorine is created equal. There are several different forms and types, each with its own set of characteristics. Let’s dive into the most common types of chlorine, pros and cons and the byproducts each type leaves behind.

Granular Chlorine Products (Calcium Hypochlorite or Sodium Dichlor) READ THE INGREDIENTS. 

Granular chlorine is a popular choice for many pool owners due to being readily available at local pool stores and big box locations, it’s ease of use and effectiveness. granular chlorine can be added directly to the pool water where it dissolves and begins sanitizing immediately.

#1 Calcium Hypochlorite:

With a high level of available chlorine, Calcium Hypochlorite is a strong and fast-acting chlorine source. It’s typically used for weekly use and shock treatments.


– Quickly increases chlorine levels.

– Generally, less expensive than other forms.

– Readily available at local big box stores.


– Can increase calcium hardness levels, leading to scale or calcium buildup around the tile line and on water features.

– Increased Calcium Hardness Levels make it harder to balance pool water.

– Needs to be pre-dissolved to prevent bleaching of the pool liner or surface.


#2 Sodium Dichlor:

Stabilized chlorine that is ideal for daily or weekly chlorination. It dissolves quickly and has a lower pH, which can reduce the need for additional pH balancing.


– Stabilized, meaning it lasts longer under the sun’s UV rays.

– Dissolves quickly and doesn’t require pre-dissolving.


– Can be more expensive.

– Overuse of stabilized chlorine can lead to a build-up of cyanuric acid. Sodium Dichlor contains Cyanuric Acid aka Stabilizer. Sodium Dichlor should not be used in conjunction with TriChlor Chlorine Tablets which are also stabilized. Your Cyanuric Acid Levels will skyrocket.


#3 Liquid Chlorine aka (Sodium Hypochlorite)

Liquid chlorine is essentially bleach at a higher concentration.


– Readily available and easy to pour into your swimming pool.

– Doesn’t add calcium hardness or cyanuric acid to the water.


– Has a short shelf life compared to other forms.

– Can be cumbersome to handle and store.


#4 Chlorine Tablets (Trichlor Chlorine Tabs or Calcium Hypochlorite Tabs)

Chlorine tablets are a convenient way to maintain a steady level of chlorine, as they dissolve slowly over time. They are usually placed in a floating dispenser or automatic chlorinator. Chlorine Tablets must NEVER be put in the skimmer basket. High levels of chlorine travel through the plumbing and into pumps and heaters which can cause damage to the entire system including the plumbing especially if the pool builder used flexible PVC

Trichlor Chlorine Tabs: Trichlor tabs Contain cyanuric acid which protects chlorine from sunlight degradation.


– Provide a slow and steady release of chlorine.

– Easy to use and doesn’t require daily attention.


– Can lower the pH of the pool water.

– Over time, cyanuric acid levels can become too high, reducing chlorine’s effectiveness. Chlorine Tabs are to be used during the months of May through September. They are designed to be used at a rate of 1 tablet weekly per 10,000 gallons of water. Chlorine tablets are not designed to be used as your sole source of chlorine. Do no stack your chlorinator full of tabs each week and walk away. Your cyanuric acid level will increase very quickly. High Cyanuric Acid will make it very difficult to balance your pool water, will cause algae buildup and will damage your pool surface whether you have a vinyl liner, gunite or fiberglass pool.

Click Here to read more about Cyanuric Acid in one my latest blog posts.


Calcium Hypochlorite Tabs:

Similar to their granular counterparts, but in tablet form.


– Convenient and easy to use.

– Does not contain cyanuric acid.


– Can increase the calcium hardness in the water.

– Requires a special erosion feeder to dispense.

Calcium Hypochlorite Tablets require special equipment. Cal Hypo Tabs must never be added to a traditional chlorinator and must never be used in conjunction with standard trichlor chlorine tablets. Cal Hypo and TriChlor Tabs do not get along and will cause a chlorine gas explosion. The same goes for using granular calcium hypochlorite together with TriChlor Tabs. Granular Cal Hypo must never be added to a skimmer especially if the pool has a traditional chlorinator containing trichlor tabs. The same explosion can occur! Granular Cal Hypo must be pre-dissolved before adding to a pool. Cal Hypo Granules can get stuck in pool filters which can slow or cause problems with filtration and circulation.

Why DIY Pool Owners Must Know about Chlorine

Understanding the type of chlorine is not just a matter of keeping your pool clean or clear; it’s about maintaining the balance of your pool chemistry. Using the wrong type, or the wrong amount, can lead to issues we discussed above:

– Increasing Calcium Hardness Levels

– Increasing Cyanuric Acid (Stabilizer Levels)

– Skin and eye irritation for swimmers.

– Corrosion of pool equipment and surfaces.

– Ineffective sanitation, which can pose health risks.

DIY pool owners must also consider factors like the size of their pool, the frequency of use, the local climate, and the existing water chemistry when selecting a chlorine product.

In conclusion, the most important thing for DIY pool owners to know is not just that they need to use chlorine, but which type of chlorine is best suited for their specific pool and current water chemistry. Each type has its pros and cons, and the right choice depends on various factors including cost, convenience, and the specific needs of the pool. A well-informed DIY pool owner is the one whose pool remains a source of joy and relaxation, not stress and extra work. Remember to always handle chemicals with care, NEVER mix chemicals together and to follow the manufacturer’s instructions for safe use. Happy swimming!

P.S. I care for over 80 pools weekly and the best chemical combination is to use liquid chlorine along with trichlor chlorine tablets when needed. This gives me the ability to test and manually adjust calcium hardness and cyanuric acid levels.

Comment below any of your questions or concerns. I look forward to hearing from you.


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