What type of Hot Tub Chlorine do I need? Tablets, Granules & Shock Explained

There are several different types of hot tub chlorine that can be used to sanitise your water, killing off unwanted bacteria and keeping your hot tub environment healthy. But new hot tub owners can easily become confused with so many hot tub chemicals to choose from. Each have their purpose and are all subtly different.

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Hot Tub Chlorine Tablets - Slow Dissolving Chlorine

One of the most widely used and simple sanitisers to use is hot tub chlorine tablets. But there are some advantages and disadvantages.

Pros of Hot Tub Chlorine Tablets

Hot tub chlorine tablets are slow dissolving and provide an ongoing and gradual sanitisation. Slow dissolving hot tub chlorine is good for not having to check the spa so frequently. It is usually added in a hot tub chlorine dispenser (sometimes referred to as a hot tub chlorine floater).

Cons of Hot Tub Chlorine Tablets

However there are some problems to be expected when using hot tub chlorine tablets.

Because they are slow dissolving, they are not good as a problem solver or for getting the chlorine level up quickly in to the recommended zone on your hot tub test strips.

Additionally, slow dissolving hot tub chemicals will result in released gasses being trapped between the hot tub cover and the waterline. This can eventually lead to damage to the cover and also ruin the walls or liner of your hot tub. Especially in a vinyl spa, we do not recommend excessive use of hot tub chlorine tablets.

What size chlorine tablets are used in hot tubs?

There are two sizes of chlorine tablets that are generally sold. Large 200g tablets which are for swimming pools with a larger volume. And 20g tablets which are much smaller (around the size of a 10p coin) which are used in hot tubs. These are usually called “mini-tabs” or “mini-tablets”.

How to use hot tub chlorine tablets?

Always dose sanitisers and other hot tub chemicals as guided by testing. Be sure to use a trusted brand of hot tub chlorine test strips. These will tell you when the levels are too low, just right, or dangerously high. Place the tablets into your hot tub chlorine float, and check them when using the spa and throughout the week to ensure there is always a little bit of undissolved tablet remaining at all times. If levels are high you can temporarily remove the float, being careful not to drip chemicals directly on to eyes or skin.

How many hot tub chlorine tablets should I use?

This will depend on too many factors to say. Water volume and how often you use the spa, as well as other maintenance and what other products you are using, and even what contaminants enter the water will effect the requirements. However, you will quickly get a feel for how many to add to get a good reading on the strips, and how often you need to add them. And you will adjust according to the problems you encounter. Always be guided by the strips.

Hot Tub Chlorine Granules - Fast Dissolving Chlorine

Another of the most widely used and simple sanitisers to use is hot tub chlorine granules. As with tablets, there are some advantages and disadvantages to using only chlorine granules.

Pros of Hot Tub Chlorine Granules

Hot tub chlorine granules are fast dissolving and provide immediate sanitisation. Fast dissolving hot tub chlorine is good for getting chlorine levels up to where you need them instantly. It is not added in a hot tub chlorine dispenser. Instead it is added directly to the water. Also, being fast dissolving results in much quick off-gassing of any chemical fumes. And less is trapped between the cover and the water line.

Cons of Hot Tub Chlorine Granules

If you do not use hot tub chlorine granules in conjunction with hot tub chlorine tablets, you will have to check the spa more frequently. Because they are fast dissolving, they can dissipate faster than tablets. However, if you are using your spa frequently enough to stay on top of testing and dosing, hot tub chlorine granules might be the easier option.

How to use hot tub chlorine granules?

Ideally, take a bucket of water out of the spa and add hot tub chlorine granules to the water. You can stir with a stick or a wooden spoon and then poor the solution back in to the hot tub. After you have added the granules, turn on the pumps and open any air valves or water jets. Create some movement and circulation in the water to help dissolve and mix the solution with the rest of the water. Let it run for 15 minutes with the cover off to allow gases to escape.

When should I add hot tub chlorine granules?

With granules we advise little and often. Which is great for regular spa users. Try to test before you get in. If necessary, dose when you get out. If you are using the hot tub every 2-3 days you are not likely to run in to low sanitiser level problems. Ultimately, be guided by your test strips and try to check frequently.

Hot Tub Chlorine Shock - Problem Solving & Weekly Boost

Hot tub chlorine shock is a problem solver and also used for a weekly boost, like a second measure to ensure your spa remains totally bacteria-free. It is referred to as non-stabilised chlorine, which simply means it isn’t designed to hang about for days after it is used. Instead, it burns off fast.

Why use hot tub chlorine shock

Why? Because it enables you to dose to unusually high levels, and quickly return to levels that are again safe for bathers. Chlorine tablets and chlorine granules are both stabilised, which is the exact opposite. And if you tried to super-dose with it, you could be waiting many days before chlorine levels came back down into the hot tub test strips “ok” zone.

Some people prefer hot tub non-chlorine shock as an alternative shock treatment for hot tubs, because it allows bathers to enter the water again the same day as dosing.

How to use hot tub chlorine shock

Hot tub chlorine shock is also sold in granules. Sometime is it referred to as granular shock chlorine. When shocking a hot tub with chlorine shock granules, always refer to the packaging and either pre-dissolve in a bucket or add it directly to the hot tub water. Turn on the pumps to give it a good circulation and ensure every granule dissolves instead of sitting on the seats or floor. Do not re-enter the spa until a test strip provides a safe reading. Do not use a chemical floater.

Hot Tub Chlorine Reducer - Hot Tub Chlorine too high?

One last product to mention is hot tub chlorine reducer. This can be useful. Mistakes happen. People confused chlorine granules with chlorine shock. Sometimes a second person may come along and dose a spa that was already done. Rather than wait a long period of time for chlorine levels to return to safe levels, you can use this product to reduce them. Even if you have to quickly order it online, with a fast delivery it is still going to be a faster solution preferable to just waiting, or conducting a complete water change.

Hot Tub Chlorine Levels

Whether you use hot tub chlorine or bromine, you should always be using the associated type of hot tub test strips. Chlorine test strips indicate the levels at which you are dangerously low and at risk of harmful bacteria growing in the water. They show you when hot tub chlorine levels are dangerously high and unsafe for bathing. And they have an “OK” zone indicating the ideal levels.

It is vital to keep your spa water at a safe level of 3-5 parts per million (ppm) for free chlorine.

Read our guide about hot tub chlorine and the difference between hot tub chlorine granules, tablets, shock, stabilised and non-stabilised. Learn how to keep a healthy hot tub environment.Read our guide about hot tub chlorine and the difference between hot tub chlorine granules, tablets, shock, stabilised and non-stabilised. Learn how to keep a healthy hot tub environment.
Read our guide about hot tub chlorine and the difference between hot tub chlorine granules, tablets, shock, stabilised and non-stabilised. Learn how to keep a healthy hot tub environment.