All pool owners know the struggle of keeping your pool clean. Between checking your pool’s pH and chlorine levels and adding chlorine treatments which can make your pool unusable for a while, it can be a tiresome job. 20gr pool tablets are an effective, low-maintenance solution for keeping your pool clean and swimmable due to their slow release.

The recommended amount of chlorine tablets for a swimming pool is one 20gr tablet for every 1000 gallons of water. You can round up if your pool doesn’t hold exact multiples of 1000. Using the correct number of tablets is essential for keeping your pool clean and still being able to swim in it.

20gr chlorine tablets

Using chlorine to clean your pool can be tricky. It’s essential to know how much to use in your pool; otherwise, your pool will stay dirty, or its chlorine level will be too high to swim in. On the other hand, using 20gr chlorine tablets effectively in your pool will make swimming and pool care a breeze.

Here’s a guide on how many 20gr chlorine tablets you should use for different pool sizes.

When Should You Use 20gr Chlorine Tablets For Your Pool?

Chlorine removes germs from your pool that cause illness and make it dirty. If your pool looks murky or green, it’s time to add some chlorine. Even if it is clean, chlorine helps to keep it that way. You can also use chlorine to treat pools where the water is entirely dark green. However, a chlorine shock treatment is necessary in these cases to dissolve most of the algae and dirt. 

Using tablets pool

Keeping your pH and chlorine levels within the correct range is essential. The water’s pH level refers to how acidic or basic it is on a scale of 1 to 14. The recommended pH level of a pool is between 7.2 and 7.8. If the water is too acidic, it can cause skin and eye irritation and start eroding the pipes for your pool. If the pool’s water is too basic, it can also irritate your eyes and skin, and disinfecting it will be more difficult.

Chlorine is acidic, which makes it great for cleaning your pool but it can cause skin and eye irritation. It may seem like adding a massive dose of chlorine to your pool will clear it up faster, but when the chlorine levels are too high, you won’t be able to swim in it. On the other hand, when the chlorine level is too low, dirt and germs can grow more freely.


The ideal chlorine level of a swimming pool is between one and three parts per million (ppm). Chlorine dissolves faster in the sun, so in sunny months you’ll want to keep your chlorine level closer to three ppm. Maintaining the correct level may become arduous if you add chlorine powder scoops to your pool, as the powder form of chlorine is typically unstabilized. This is where chlorine tablets come in handy.

Chlorine tablets disperse slowly to maintain a constant chlorine level in your pool. This prevents dirt from building up and gives you peace of mind. When using chlorine tablets, it’s best to check your chlorine and pH levels every three to five days. Chlorine tablets will dissolve after a few days, and then you can add more to maintain your chlorine levels and keep your pool clean.

Testing kits allow you to test your pool’s pH and chlorine levels quickly. They provide a color chart to see your levels and whether they need to be adjusted. Some test kits give you strips to dip in the water, while others require you to drip some pool water into a container with their chemicals. In both cases, the solution or strips will change color depending on your pool’s pH and chlorine levels.

How Many 20gr Chlorine Tablets Should You Use For Your Pool?

When you want to add chlorine tablets to your pool, there are various factors to consider. The size of your pool and whether you’re using a dispenser or the skimmer will give you a good idea of how many tablets to add to keep your chlorine levels correct and keep your pool clean.

However, the most important thing you’ll want to look at is how much water is in your pool.

Knowing the correct number of chlorine tablets to add to your pool is essential so that you don’t under or over-chlorinate your pool. The size guide above should give you an idea of how many 20gr chlorine tablets to add to your pool if you drop them into your pool’s skimmers. If you use a floating chlorine dispenser, adjust the opening to allow the correct amount of chlorine to filter out.

The ideal amount of water per 20gr tablet is 1000 gallons rounded up. This means that if your pool is 4750 gallons, you should add five 20gr chlorine tablets to maintain the correct chlorine levels and keep your pool clean. Chlorine tablets dissolve slowly so that the chlorine will be filtered into the pool constantly and evenly over a couple of days. 

If you’re putting the chlorine tablets into your skimmers, you should check how much is left after three to five days and test your water’s pH and chlorine levels. If there are some left, come back later to replenish the supply. It’s important not to add more before the rest have dissolved because your pool’s chlorine level can get too high. This will make it uncomfortable to swim in.

Swimming pool

If you don’t know how many gallons of water are in your pool, it’s not difficult to work out. The formula changes for pools of different shapes and whether the pool is above-ground or inground. Each of these formulas should give you the estimated number of gallons in your pool:

  • Rectangular pools: length x width x average depth x 7.5
  • Oval pools: longest length x fullest width x average depth x 6.7
  • Round pools: diameter x diameter x 5.9

Size Guide To Add 20gr Chlorine Tablets To A Pool

Length x Width x Average Depth (ft)GallonsNumber Of Tablets
10 x 10 x 53,7504
12 x 24 x 510,80011
16 x 32 x 519,20020
18 x 36 x 524,30025
20 x 40 x 530,00030

What Lowers Your Pool’s Chlorine Levels?

Keeping your pool’s chlorine level within its ideal range is pretty easy, and there are just a few things to keep an eye on that can reduce the chlorine in your pool. Having these in mind, keeping your chlorine level in range should be a breeze.

More prolonged sun exposure and a higher UV index, in other words- more intense sun exposure, will lower the chlorine level of your pool. Bugs, leaves, and general dirt will also lower the chlorine level. So using a pool cover if you have one is a good idea in summer.

Chlorine dissolves when it breaks down dirt, so the more dirt that gets into your pool, the more chlorine you’ll need. 

Another factor to consider is how much the pool is being used. If you use the pool daily or many people use it regularly, the chlorine level will also decrease. It’s trying to break down contaminants on our bodies like shampoos, suntan lotion, and others. It will dissolve faster than usual since there are more contaminants to take care of. 

What Are 20gr Chlorine Tablets For Pools?

A chlorine tablet is a stabilized form of chlorine that is compressed into tablet form, as the name suggests. Chlorine is extremely sensitive to UV rays and disperses very quickly in sunlight. Cyanuric acid is mixed into chlorine tablets to act as a stabilizer. It prevents the chlorine from dispersing too quickly in the sun so that it has time to get rid of any dirt in your pool, and your chlorine level doesn’t drop too quickly.

The slow release, low maintenance, and low cost make it a popular choice among pool owners. The chlorine filters throughout your pool over a couple of days, so you only need to check your pool’s pH and chlorine levels once a week to ensure you’re using the correct amount. 

If you find that your pool is still getting dirty, it may be a good idea to add a shock treatment of unstabilized chlorine to your pool to help get rid of the persistent dirt. Although the shock treatment will make your pool unusable for around 24 hours, it will remove any excess dirt that your chlorine tablets have been unable to remove. 

Chlorine shock treatments use unstabilized chlorine, which is sensitive to sunlight and will disperse quickly. To get the most out of your shock treatment, try adding it in the evening or at night to let it clean your pool for longer. After twenty-four hours, test your pool’s chlorine levels to see if swimming is safe. Check which chlorine chemicals can be used together, as mixing different ones can be dangerous.


Chlorine tablets are an easy way to maintain your pool without having to spend time on it every day. 20gr chlorine tablets are usually mixed with cyanuric acid, which acts as a stabilizer to slow down the chlorine’s average rate of dispersion.

The chemicals are then pressed into tablet form. The typical rule of thumb for adding 20gr chlorine tablets to your pool is one tablet for every 1000 gallons of water. 

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