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What Chemicals Do I Need for a Hot Tub?

So you finally took the plunge and bought the hot tub right for you. Now that you finally own the hot tub of your dreams, you’ve also found the perfect location for it and are anxiously awaiting for the moment to climb right in and relax. Sounds simple, right? You may have forgotten one essential thing that every hot tub owner should remember: hot tub chemistry.

Much like a swimming pool, managing the chemistry in your hot tub is pretty simple once you understand what needs to go in (and go out) in your hot tub water. Maintaining the spa chemicals in your hot tub include alkalinity, pH levels, sanitizers, and shock treatments. Don’t be frightened by these terms--you don’t need a PhD in Chemistry to understand what goes inside your hot tub. This article is here to help you become an expert on properly maintaining your hot tub!

Spa Metal Free

Spa Metal Free

If you are filling up for the first time or reopening your hot tub, let the spa water circulate for about an hour and then use Spa Metal Free. Spa Metal Free is very handy as the metals are present in tap water, which is why Metal Free is the perfect solution to neutralize the water before any chemicals are adjusted. Let the Spa Metal Free circulate for about 4-6 hours before doing anything else.

Spa Test Kit

spa test strips

Take a water sample (we recommend scooping up the water about a foot down from the hot tub) so that you’re able to determine your current water chemistry. One of the four most common chemicals tested in a spa test kit are chlorine/bromine, pH, alkalinity and calcium hardness.

Keep in mind these recommended ranges for balanced water inside your hot tub. This will be imperative when adding the proper chemicals. After getting a good reading on your water chemistry, we recommend pouring Calcium Hardness first, then a pH Balancer and then a Sanitizer.

Type Recommended Range
pH    7.2-7.8
Total Alkalinity   80-120 ppm
Calcium Hardness   150-400 ppm
Metals   None
Total Dissolved Solids   Not More Than 2000 ppm
Water Temperature   No Hotter Than 104°

If you need help testing and balancing your spa water, just bring a sample to your local Leslie's store. Our knowledgeable pool experts will review the results of the Leslie's AccuBlue® water test to determine the best treatment options for 10 different aspects of water chemistry. You'll get a detailed, customized water treatment plan with step-by-step instructions to get your spa water back on track.

Spa Calcium Hardness Increaser

Calcium Hardness

Sometimes referred to as Total Hardness, Calcium Hardness is the amount of calcium and magnesium dissolved inside your hot tub water. Did you know that calcium is found is almost every water supply? Including the water you use in your home? Measuring Calcium Hardness is the best way to know just how much calcium is in your water.

When your calcium hardness levels are too low in your hot tub, unfortunately your spa is susceptible to erosion and damage. To avoid this, we suggest adding calcium hardness to your water in order for it to become leveled at the perfect range.

Leslie's Spa pH Up

Total Alkalinity and pH

We’re talking about both Total Alkalinity and pH because they work very close together when it comes to spa chemistry. Alkalinity is the measured amount of carbonates and bicarbonates inside your hot tub water, which act as a buffer in order to stabilize the pH in the water. And to put it simply, pH measures how acidic your hot tub water is. See the correlation?

When the pH in your hot tub water is below 7.0, then the water becomes corrosive and can damage parts of your hot tub’s internal system. When the pH is higher than 8.0, scales, stains and cloudy water can begin to appear. A high pH can also mean too much calcium is present and can show up on your hot tub’s surfaces and inside pipes.

Leslie's Dry Acid

When the Alkalinity is below the suggested range, this will cause the pH in your water to change levels frequently and become unstable. When the Alkalinity is too high, this will cause the pH be very resistant to change.

bromine tablet sanitizer

Chlorine or Bromine: What’s the Best Option?

There has been a lot of debate when it comes to chlorine and bromine when used in a spa. In our professional opinion, we have always recommended bromine because bromine holds up better under heat and will therefore be a more effective sanitizer over time. One downfall to using bromine, however, is that it is more expensive to purchase. But we believe that the cost is worth it as bromine is a powerful sanitizer that kills bacteria and viruses, has an odorless scent (unlike chlorine), and is less likely to cause skin irritation.

Bromine it is!

Fresh N Clear Oxidizing Shock

And Finally: Shock!

An integral component when it comes to maintaining the water inside your hot tub is to shock it. Shocking your spa water is necessary when you’re opening your hot tub, after a period of inactivity or even after heavy use. It’s critical that you shock your spa water to keep it safe and free from all contaminants. 

Let’s break down the reason why shocking your spa water is important:

Shock kills bacteria
Chlorine and bromine based shock easily kills bacteria that lives inside your water.

Removes Bromamines and Chloramines
Adding shock to your spa water helps break the bonds that form these contaminants from your hot tub.

Insider’s Tip: Unfamiliar with the terms bromamines or chloramines? This would require an article on its own to explain, but to put it bluntly: you don’t want either of these in your pool.

Removes organic compounds from the water
If you use your hot tub often or you have 3 or 4 bathers in there at once, the level of organic compounds can spike quickly. Removing these compounds is a must for clean water.

Spa Fragrances

Spa fragrances are not a ‘need’, but they certainly are a ‘nice to have’. You’ll be surprised to know that are several kind of aromatherapy scents that are especially made for hot tubs. They range in scents and are a great addition to your relaxing hot tub time. And lucky for you, we have quite a bit of variety when it comes to spa fragrances. Check them out here!

We hope this article has covered the basics on spa chemistry and the chemicals you need to ensure that your hot tub is ready for use when you need it. With a hot tub, the rest and relaxation is endless, so might as well enjoy every minute of it!