Why you don’t need Ozone in a Hot Tub and what you should use instead

Why you dont need Ozone in a hot tub

One of the things that I often get asked about is using Ozone on a Hot Tub. In this article I am going to explain why you don’t need Ozone on your Hot Tub and what a better alternative is.

What is Ozone on a Hot Tub and How Does It Work?


Ozone sanitization in hot tubs works by introducing ozone gas (O3) into the water through an ozone generator. The ozone gas is created by passing air through a high-voltage electrical field, which splits the oxygen molecules (O2) into individual atoms. These atoms then recombine to form ozone (O3).


Once the ozone gas is introduced into the water, it reacts with any impurities or bacteria present, breaking apart the ozone molecule and releasing the extra oxygen atom. The oxygen atom then attaches itself to the impurities or bacteria, neutralizing them.


This process is called oxidation and it helps to kill bacteria, viruses, and other microorganisms in the water, making it much cleaner and safer for use. The neutralized impurities and bacteria can then be easily removed from the water through the hot tub’s filtration system.


Additionally, Ozone also helps to reduce the amount of chlorine or other chemical sanitizers that are needed to keep the water clean. This can help to reduce the overall chemical levels in the water and make the hot tub experience more pleasant for the users by reducing the smell of chlorine and other chemicals.


Overall, Ozone sanitization is an effective and efficient way to keep hot tub water clean and safe for use. It is a low-cost and chemical-free alternative to traditional water sanitization methods.


So that was the “Science bit” – let me share my experience with Ozone


My Journey with Ozone, and it was a journey started out when I was building my own DIY Hot Tub. “Pool Man John” suggested that I added an Ozonator to my setup. I didn’t buy a cheap one, this was a £200/$250 Balboa unit.


From the start, this was a bit of a disaster. Connecting the unit to the Spa Pack was not a problem – this in itself was straight forward. It was everything else that is involved in setting up the system correctly.


You hear how Ozone is dangerous if inhaled, so this had me a little worried from the outset when I was trying to put the system together.


Firstly, you have to get a Hartford loop in there to stop water getting back to the unit. Then, you need a one way valve – both of these were pretty straight forward to do although they look a mess in your control room IMHO.

However, the process in which Ozone is drawn into the water is done by venturi – I just could not get this to work. Furthermore, this setup made my hot tub leak every time the jets were turned on wand water went everywhere in the control room – the pressure was just too much.


After plugging leaks left right and centre and trying to run with the unit for a month or two, I gave up.


I cut the unit out of the system, which at that point was all blocked up and full of “gunk” as it was not working correctly, and through it straight into the bin – best thing I did! Piped up the gap and guess what, no leaks!


As the unit had never worked correctly, I didn’t feel that I was missing any benefits at all from not having it – and now my hot tub didn’t leak.


For me, Ozone is a little bit “old school” an outdated means of sanitising your hot tub.


As such, in the 600+ customers I have helped at time of writing on their Hot Tub journeys, I have never specified, designed in, or supplied an Ozone unit. Plus, I have convinced anyone that has ever asked about one that they don’t need them!


What is a better alternative to Ozone in Hot Tubs?


For me, a much better option than Ozone in hot tubs is UVC – Ultraviolet.

Ultraviolet (UV) light is a type of electromagnetic radiation that lies in the spectrum between visible light and X-rays. UV light is divided into three main categories: UVA, UVB, and UVC. UVC is the most effective type of UV light for killing microorganisms, and is the type of UV light that is typically used in hot tubs.


When water flows through the hot tub’s plumbing system, it passes through a chamber that contains a UV lamp. The lamp emits UVC light, which sterilizes the water by damaging the DNA of any microorganisms present. This prevents the microorganisms from reproducing and keeps the water clean and safe for use.


The effectiveness of the UV sterilization process depends on several factors, including the intensity of the UV light, the flow rate of the water, and the length of time the water is exposed to the UV light.


In general, the higher the intensity of the UV light, the faster the flow rate of the water, and the longer the water is exposed to the UV light, the more effective the sterilization process will be.


In addition to killing microorganisms, UV sterilization can also help to reduce the amount of chemicals like chlorine or bromine that are needed to keep the water clean. This can help to make the hot tub water more comfortable to use and reduce the potential for irritation or allergic reactions.


It’s worth noting that UV sterilization should be used in conjunction with other sanitizing methods, such as chemical treatment, in order to maintain a safe and healthy hot tub environment.


UV – The Installation


The Installation of UV is pretty straight forward. The UVC units sit in series with your circulation plumbing and they should be after the heater or spa pack.


If you don’t have a circulation pump, then you should put a bypass on the UV unit to allow for adequate flow to your jets – most units have a maximum flow rate of around 80 GPM, which is not enough for your jets.


In terms of powering the unit, as they are low current draw, I like to power these directly off the circulation pump. That way, you are only ever running the unit when the water is circulating.


This may not be how the manufacturer has designed the system to work, but for me, it is an effective way of doing things.

Chemical Free Option?


UV on its own as we have established, is not an effective or I should say, Complete way of sanitising your Hot Tub. However, if you are looking to run a completely chemical free hot tub. Then here is an alternative for you. UV & Active Oxygen.


Active Oxygen Tablets


Active oxygen tablets for hot tubs are a type of sanitizing agent that are used to keep the water in a hot tub clean and safe for use. They typically contain hydrogen peroxide as an active ingredient, which acts as a powerful oxidizing agent that can kill bacteria, viruses, algae, and other microorganisms that can grow in the warm, humid environment of a hot tub.


The tablets are usually added to the hot tub on a regular basis, usually once or twice a week, depending on the usage and the number of people using the hot tub. The frequency of use, water temperature and bather load are also factors to consider when determining the appropriate dosage. The tablets are typically placed in a floating dispenser or directly into the hot tub’s skimmer.


It’s important to follow the manufacturer’s instructions for use and dosage to ensure that the water is properly sanitized. In addition to using active oxygen tablets, other measures such as maintaining a consistent pH level, keeping the hot tub clean, and regularly changing the water can also help to keep the hot tub in good condition. It’s also important to keep an eye on the hot tub’s chlorine or bromine levels, to ensure that they are within the recommended range for safe use.

It’s important to note that active oxygen tablets should not be used in combination with chlorine or bromine, as the combination can create harmful by-products.





Can I Help You?

If I can help you in any way I would love to hear from you. You can get in touch using the form below.

Thanks - Andi


Hi, Andi here. I own Buildahottub.com and also write all of the articles and info pages on the site. Some years back now, I built my own hot tub but struggled to find the information I needed. So, once my tub was complete, I started this website to help others in their own pursuit of hot tub and plunge pools DIY building information.

Today, I've helped over 1000 DIY customers just like you all over the world build hot tubs and pools. Have a good look around the site, there are lots of resources here. Please do get in touch if I can help you. - Cheers, Andi

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