Hot Tub Chemicals: A Complete Guide for Beginners

A hot tub provides an excellent means of unwinding after a long day, offering a soothing escape to immerse yourself in. However, before you indulge in this relaxing experience, it is crucial to confirm that the water is both clean and safe for use.

In this informative blog post, we will delve into the essential hot tub chemicals required to maintain a pristine and secure environment for your hot tub. We will not only discuss their proper usage but also address common issues and effective solutions to keep your hot tub in top condition.

Dive into this comprehensive guide to gain insight into the world of hot tub chemicals and ensure a safe and enjoyable soak every time.

Sanitisers

Chlorine in hot tubs

Chlorine is a sanitising agent used to kill bacteria and other organisms in the water. Hot tubs using chlorine must maintain a level of chlorine that keeps the water clean while still being safe, this is generally between 1 and 3ppm (parts per million).

If the chlorine level falls too far below the recommended amount, it can cause bacteria and algae to grow, while chlorine above this level may irritate and dry your skin and hair.

Using chlorine for the first time

The recommended dose for new hot tubs is one teaspoon for every 500 litres. This should be added to a full hot tub and allowed to sit for at least an hour to allow excess chlorine to dissipate. Before you climb in, it's worth testing the water to with a chlorine testing strip to ensure it's at the appropriate level. It's important the hot tub is uncovered and well ventilated when you add any chemical to the water.

What is a chlorine shock treatment?

A chlorine shock treatment is the process of adding a large dose of chlorine to the water, typically 5-10 times the normal amount. This high level of chlorine will quickly kill any bacteria, diseases, organic contaminants or algae present. It's important to wait until chlorine levels have gone back down to 1-3 ppm before you dive in, as high levels of chlorine are bad for your skin, eyes and hair. This happens naturally if you leave your tub uncovered, as it dissipates over time.

Before you shock a hot tub, we recommend testing the water's pH level - it should be between 7.4 and 7.6. The recommended chlorine level for hot tubs is 1-3ppm (parts per million), which you can test with a chlorine test strip. To balance the chlorine levels, follow the instructions on the chlorine granules or tablet packaging. Add the appropriate amount of chlorine to the water for low chlorine levels. If chlorine levels are too high, it may be worth draining the hot tub and refilling it with fresh water. If the chlorine levels are deficient, you may need to shock dose the spa.

Testing your hot tub for chlorine

You can test the chlorine level in your hot tub using test strips, which are readily available online. To use a test strip, dip it in the hot tub water for a few seconds, then remove it and compare the colour of the strip to the chart on the packaging. This will give you an idea of how much chlorine is in the water and whether it needs to be adjusted.

Bromine in hot tubs

While chlorine is a popular choice for hot tub sanitising, it can be harsh on sensitive skin. Bromine is a chlorine alternative that is gentler and often longer-lasting, although it may cost slightly more. Bromine is a better choice for individuals with sensitive skin, although you may need larger amounts to have the same effect as chlorine. The safe range for bromine is 3-5ppm (parts per million) for a regular hot tub or 1-3ppm for a hot tub with an Ozonator.

Using bromine for the first time

Bromine is typically used in tablet or granule form, which can be added to the water using a dispenser. The recommended dose for new hot tubs is one teaspoon per 500 litres, although you may need more if the pH level is high. Bromine tablets will dissolve slowly over time, so you will need to regularly test and top up the level to maintain effective sanitisation. You can test the bromine level in your hot tub using test strips, which are readily available online.

Testing your hot tub for bromine

To use a test strip, dip it in the hot tub water for a few seconds, then remove it and compare the colour of the strip to the chart on the packaging. This will give you an idea of how much bromine is in the water and whether it needs to be adjusted. If the bromine levels are too high, it may be worth draining the hot tub and refilling it with fresh water. If the bromine levels are deficient, you may need to add more tablets or granules.

Biguanide

Biguanide is a non-chlorine sanitiser that kills bacteria, much like chlorine and bromine. It does not need to be used as frequently as chlorine or bromine, is odourless at every stage, and makes the water feel smoother to you and your hot tub guests. On the other hand, biguanide usually costs more than chlorine and bromine, and it has also been known to cause deterioration in some spa parts like rubber gaskets and certain plastics. The proper biguanide level is 30 to 50ppm. Regardless of which sanitiser you use, your hot tub water’s alkalinity and pH will need to be balanced for the sanitiser to do its job.

Oxygen

Oxygen is a milder solution to chlorine and bromine and is designed for use in a hot tub for those with sensitive skin. You will need to use oxygen tablets in conjunction with oxygen liquid. The advantage to using oxygen tablets in your hot tub is that one 20g tablet and 15ml of oxygen liquid should last one week in 1,500 litres of water. The proper oxygen level should be between 5-10mg/l, and active oxygen should be used weekly to ensure the hot tub is well maintained.

Minerals & more

Calcium

Calcium is a mineral that is naturally found in water and having the proper level in your hot tub water is essential, as too much or too little can cause problems. Although all water contains trace amounts of calcium, homes in the south of England generally have harder water than elsewhere, which means it's especially important to test for calcium hardness.

The level of calcium hardness in your hot tub should generally not exceed 75-100ppm (parts per million). Too much calcium in your water can lead to cloudy water and scaling on your hot tub and its components. If this happens, the best solution is to drain your hot tub, scrub it, and start over with fresh water. To keep the calcium level in your hot tub water balanced, you will need to use a calcium hardness increaser or water softener as needed.

Enzymes

Some people use enzymes in their hot tub because they can help maintain sanitiser levels in the water, as well as break down organic material, including contaminants like body oils and lotion. However, using enzymes is unnecessary if you keep your sanitiser levels balanced and regularly drain and clean your hot tub. It is generally recommended that you do this every few months at least.

Defoamer

Excessive hot tub foam can be unsightly and difficult to clean up, and it also indicates an unbalanced hot tub. Defoamer will help keep your hot tub water clean and clear by breaking down the foam and preventing it from accumulating. It can also help identify other water problems, such as low calcium levels. Low calcium levels can cause foaming, as can high oil levels and other contaminants.

Add the defoamer to the hot tub water and circulate it for a few minutes to distribute it evenly. You will usually only need a small amount, such as a capful. Defoamer is available in different concentrations, so follow the instructions on the packaging.

Balancing your hot tub's pH

You may not have encountered pH since school, but it's actually incredibly easy to understand. Neutral water has a pH of 7 and is neither acid nor alkaline. Anything with a pH below 7 is considered acidic, and anything with a pH above 7 is considered alkaline. pH is important in hot tubs because it affects how effective your sanitiser is. If the pH is too high, your sanitiser will be less effective, and if it's too low, it can be corrosive. The ideal pH range for hot tubs is 7.2-7.6.

pH test strips are the easiest way to test your hot tub water's pH levels. You can also use a digital pH meter, which is more accurate but also more expensive. Test your hot tub water's pH levels at least once a week and adjust as needed.

How to balance your hot tub's pH

Balancing the pH level for your hot tub is pretty easy. If the pH is too low, you will need to add an alkali, such as sodium bicarbonate (baking soda). If the pH is too high, you will need to add an acid, such as muriatic acid or white vinegar. Test the water regularly to maintain pH levels within the ideal range of 7.2 – 7.6pH.

Hot tub filter care

The primary purpose of a hot tub filter is to remove dirt and debris from the water. If these particles are not removed, they can cause the water to become cloudy and unclean. Additionally, if the filters are not cleaned regularly, they can become clogged and restrict water flow.

To clean the filters, you will need a specially formulated filter cleaner or a natural cleaner like vinegar. This cleaner will break down oils and dirt from the pleats and give the filter a deep clean. It is vital to allow the filter to air dry completely before putting it back into the hot tub.

It is best to soak your hot tub filters in a bucket of cleaning solution for 30 minutes to an hour to remove dirt, debris and natural contaminants from the filters. After soaking, rinse the filters thoroughly (a garden hose is great to blast the filters completely) and allow them to dry completely before using them again.

In conclusion

Hot tubs are a great way to relax and unwind, but it is important to keep them clean and well-maintained. By following these simple tips, you can enjoy your hot tub for years to come.

To learn more about cleaning and maintaining your hot tub, read our complete guide to hot tub maintenance.

FAQs

How should you store hot tub chemicals?

Chemicals must be stored in a cool, dark, and dry place to reduce the risk of dangerous reactions. Provide plenty of ventilation in the storage area to avoid dangerous fumes accumulating, paying close attention to product label instructions. Never hold any chemicals on the floor or above your head. Keep chemicals away from anything flammable, such as heaters or stoves. Do not reuse or switch containers as doing so could lead to a dangerous reaction.

How long do hot tub chemicals last?

The longevity of your hot tub chemical depends on the type of chemical and how it has been stored. To ensure you prolong the shelf life, you should always keep hot tub chemicals away from heat and moisture. It would be best if you always referred to the manufacturer’s guidelines on the packaging. Depending on the type of chemical, hot tub chemicals can last from a few weeks to several months. Proper storage is key to prolonging the shelf life of your hot tub chemicals.