- Categories: Spa Cleaning
Spa sanitiser: how to keep your spa water clean
If there’s one way to keep your hot tub clean, it’ll be with good ol’ spa sanitiser. Because without it, your prized hot tub will quickly turn into a cesspool of grotesque gunk, and we think you should probably leave that sort of science experiment up to actual scientists.
Although the thought of spa sanitation might turn your brain into a whirlpool, this guide is going to put you on the straight and narrow. So if you’re a new spa owner looking for the best spa sanitiser or your dirty spa water has you stumped, we’re here to help you clean up this mess.
In this spa sanitiser guide, we’ll cover:
Let’s dive in.
What is a spa sanitiser?
A spa sanitiser is essentially a chemical compound based on chlorine or bromine. Besides, it comes in different dispensing methods: tablets, granules and even as a filtration system. Even though the outcome of bromine and chlorine are very similar, they still have their differences, which we will soon see.
A spa sanitiser has one main objective: to kill harmful bacteria and organisms before they multiply and build up in your spa water, causing havoc in every nook and cranny.
How chlorine as a spa sanitiser works
Chlorine molecules follow a process called oxidation, which means they’re a sneaky spa sanitiser.
When it’s added to your spa water, the chlorine molecules combine with bacteria and steal their electrons, subtly deeming them powerless.
After chlorine has taken its loot from one bacteria, it changes into a waste product known as chloramine. The smelliness that most of us mistake for chlorine is actually the smell released by chloramines, and you won’t want that to stick around.
Chlorine shock (sodium dichlor) oxidizes the chloramines into the air, or in other words, gases them out. Good riddance. Once its life cycle is complete, a new batch of chlorine is introduced, and the cycle starts afresh.
Chlorines attack bacteria only once, and then become ineffective chloramines, so they smell and they’re useless.
How bromine as a spa sanitiser works
Bromine molecules follow a process called ionization, which means they’re an aggressive spa sanitiser.
When it’s added to your spa water, bromine molecules combine with bacteria and rip apart their chemical bonds, basically annihilating them. After bromine has eradicated the invader, it leaves behind a by-product known as bromimines.
Unlike chlorine, bromine continues to work again and again, you’ll just need to oxidize the by-product, bromimine, with non-chlorinated (potassium monopersulfate) shock treatment, so they don’t build up. Not only are bromine molecules hard workers, they also don’t tend to smell as much.
What is the best spa sanitiser?
All things considered, the best spa sanitiser has to be bromine.
But chlorine is also a strong contender. It just depends on your preferences and where you’ve put your spa. Check out the pros and cons between the two in the table below:
| Bromine | Chlorine | |
|---|---|---|
| Pros | bromine molecules can be reused. | faster-acting. |
| less smelly. | cheaper. | |
| more stable in higher temperatures. | easy to dose. | |
| best spa sanitiser for sensitive skin. | breaks down slower from UV light from the sun. | |
| lower pH. | ||
| Cons | slower-acting. | chlorine molecules cannot be reused. |
| more expensive. | more smelly. | |
| one dispensing method. | less stable in higher temperatures. | |
| breaks down quickly from UV light from the sun. | worst spa sanitiser for sensitive skin. | |
| higher pH. |
You can probably see now how bromine comes out on top. For those of you leaning more towards chlorine, we’ve still got a few other suitable chlorine options for you to choose from in the section coming up next.
What should I use to sanitise my hot tub?
There are plenty of spa sanitiser options to use in your hot tub.
If you want to use chlorine
Like we said, plenty of options swimming around here. First up, the tablets and granules:
- OSPA Sanitiser: A granular spa sanitiser and oxidiser with lower pH.
- Stabilised chlorine tablets: Spa sanitiser tablets for outdoor spas.
Missing your lithium-based chlorine?
Back in the good old days, lithium sanitiser was flying off the shelves. It was fast dissolving, and easy to apply to the pool. As it was a little more pure than sodium based spa sanitiser it meant the water in the spa could last a little longer before being changed.
But those days came to an end. The price of lithium was too high to be used in a humble sanitiser, now that products such as batteries have become increasingly popular. Everyone had to make a change if lithium based chlorine had always been their go to.
But good news! Lithium is coming back! Watch this space or check with your pool shop if you prefer lithium sanitiser and want to change back.
If you want to use bromine
As for bromine, it only comes as a spa sanitiser tablet. But that’s a good thing. Unlike granules, you won’t need to fumble around with measuring and mixing, turning your serene spa area into a laboratory. You’ll just need the bromine tablets and the feeder.
Don’t let the limited options of bromine put you off, just remember that bromine is the best spa sanitiser to use.
Bromine works a little differently from chlorine in the spa. With bromine, you create a “bromine bank” in the water, and then only need to top up the bank. That means once you’ve got the right amount of bromine in the water, you can reduce the number of tablets you use.
Unlike chlorine which gets consumed treating the water in the spa, bromine will go from an active to an inactive state while staying in the water. You reactivate the bromine when you shock-dose the spa with chlorine.
All clear?
Bromine, chlorine, whichever one you stick with, the main takeaway is to choose the most suitable option for your circumstances and apply them properly. Remind to read the manufacturer’s instructions, and always stay safe when adding them into your spa water.
Keep on top of all of these tips and your spa should remain clean and clear. For further information, you can also read our spa pool cleaning guide.
Happy soaking.
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Hey! I'm Adrian, founder and pool expert here at Dolphin Pacific. I love spending time with family, fishing, and have been known to brew my own beer.
