Hot Tub Water Treatment by Chemicals

What Chemicals Do i Need for a Hot Tub? DIY Dummies Guide

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Preventing problems before they occur will give you more enjoyment from your sparkling clean hot tub. In this post, you will learn about what chemicals [chlorine, bromine, test kits] you need and how and when to use them.!

So you got yourself a hot tub spa. You love the way it looks. You feel so relaxed lounging in the comfortable seats. Your bones and muscles feel so good when the warm water massages every inch of your tired body.

So what next?

You need to make sure that you keep enjoying the joys your hot tub is offering you through proper maintenance and care.!

Otherwise, you can run the risk of:

  • Damaging your tub
  • Irritated skin and eyes
  • Excessive use of chemicals

Keeping your water appropriately tested and using the correct chemicals is very important. You risk getting sick or experiencing chemical burns otherwise. Remember, this isn’t a bathtub where you drain the water right after using it.

The water filter should be changed or at least rinsed on a daily basis, and testing should be done weekly.


Tip: To help your water stay cleaner, don’t use lotions or similar products on your skin before getting into the tub. You may even want to consider showering before entering the hot tub.

So to keep your hot tubs running smoothly, you should have the knowledge of what your spa needs.

What kind of chemicals do you need to keep your water clear and fresh? What should you add to the spa water each week? How do you keep it clean? How do you care for the cover?

Caring for your spa does not have to be a problem, [however, it will save you from many problems] as long as you follow some simple instructions and if you have the right chemicals and accessories at hand.

As an owner of a hot tub, you need to ensure your hot tub water is balanced and sanitized. Sanitizing your water ensures that the water is free from bacteria and is clean and safe to use.

So, you will have to get all the right chemicals, cleaning products and accessories that are necessary to keep your hot tub spa in tip-top shape.

Yes, it does cost some money but the good thing about spa chemicals is that you don’t need large quantities to do the job right. A small bottle will last a long time because you are only treating a relatively small amount of water (compared to a swimming pool).

What do you want to control through chemicals?

You need chemicals to control and maintain the water balance for

  • pH: You have to maintain water pH between 7.2 – 7.8 for your tub.
  • Total alkalinity: The Total Alkalinity of your water should be between 80-120 ppm.
  • Calcium hardness:  Your hot tub should have the Calcium Hardness between 150-250 ppm.

In order to maintain these parameters, you need to check and monitor them. You can do it weekly or every time you use it.

How to check pH, alkalinity and calcium hardness For Hot Tubs?

By checking these parameters, you’ll know what chemicals you need. e.g. you’ll need a different chemicals for a high pH and low pH.

To do this, you will need Spa Test Strips or digital meter. The testing strips not only measure pH levels but also chlorine, bromine, and alkalinity levels which is extremely helpful. We recommend the strips over the digital meter unless you want to buy separate chlorine, bromine, and alkalinity testers.

Using pH strips is really easy. Simply dip the strip into your hot tub and the strip will change color. Then compare this strip to the color chart supplied with the testing strip kit you purchased and whatever the color matches with is what your pH is.

AquaChek Spa Test Strips

6 in 1 test strips test for:

  • Total Alkalinity
  • pH
  • Total Hardness
  • Total Bromine
  • Free Chlorine
  • Total Chlorine
Buy on Amazon

Effects of parameters and how to control them?

After checking the parameters. You have to balance out if any of them is out of range.

Understanding & Controlling pH in Hot Tubs

The range of your hot tub pH should be between 7.2 & 7.8. The ideal pH to achieve is between 7.4 & 7.6.

Running your hot tub out of these ranges can significantly damage your hot tub and create an unpleasant environment for anyone who uses it. If your pH is out of range it will also make the other chemicals you have to use less effective.

Impact of Low pH in Hot tub

  • Having a low pH means that your water is more on the acidic side and this is not good for you or your hot tub.
  • Acidic water will corrode anything that it comes into contact with, meaning it will be damaging the walls of your tub, the heating element and pump in your tub and most importantly; YOU!
  • It will damage the natural oils in your skin and can irritate your eyes.

What causes low ph in the hot tub?

There are several factors that can attribute to low pH:

  • Your water is naturally lower in pH.
  • Heavy hot tub use can lower pH as body oils and sweat will contaminate the water and lower the pH.
  • Natural contaminants such as grass and insects will lower the pH.
  • You may have used too much pH reducer.

How to raise pH in the hot tub?

The most common way to increase your tubs pH is to use a pH increaser. You simply add the recommended amount, based on how much water your hot tub has in it, and wait for it to bring up the pH.

How to raise pH in hot tub

Hot Tub ph increaser

This dry, granular increaser will gradually increase your pH.

Simply add 1 tsp per 100 gallons of spa or hot tub water to adjust your pH.

Buy on Amazon

Impact of High pH in Hot tub

Having a high pH means that your hot tub and equipment is more susceptible to scale. Scale is not good for equipment as it will build on the filters, in the pump, and in the bubble streams. All of this means your equipment will be under more strain to work normally, resulting in a less than satisfactory experience and damage to your hot tub. 

What causes high pH in hot tub?

The primary reason for a high pH and the tendency for the pH to stay high is a very high total alkalinity. Total alkalinity is the buffer to keep pH in range.

If the total alkalinity is not in range, it cannot buffer the pH to stay in the desired range for hot tubs. Hot tubs, in particular, generate a lot of bubbles and tend to have higher temperatures. This combination creates a gas called carbon dioxide very quickly.

Carbon dioxide builds up and makes the pH go up. This is why hot tub owners, on a regular basis, need to add something to lower their pH and alkalinity.

Hot tubbers that have an even harder time lowering their pH is are ones that have well water for the source water – softened or straight from the well, it generally has a high pH and total alkalinity.

How To lower Your pH in hot tub?

Decreasing your pH is similar to increasing your pH; you use a chemical. In this instance of high pH, you would use a pH reducer, according to the manufacturer's guidelines based on water volume, to reduce your pH.

lower Your pH in hot tub

Hot Tub pH Decreaser

This dry, granular decreaser will gradually reduce your pH leaving you with a perfect environment to relax in your hot tub.

Buy on Amazon

Now you know about pH and why it is important, we need to look at Total Alkalinity

Understanding & Controlling Total Alkalinity in Hot Tubs

Total Alkalinity (or TA) levels should be between 80-120 ppm (parts per million).

The total alkalinity (TA) is a measure of how much of the alkaline substances there are in the water. In hot tub water, we are concerned with bicarbonate alkalinity.

TA acts as a buffer, meaning that if your range is incorrect, you will have fluctuations in your pH and will struggle to maintain a correct pH.

The better the TA, the better your pH, the better your hot tub experience will be. When your TA is between 80 & 120 ppm it means your water ph will be more stable.

Before you adjust your hot tubs pH, you should check that the Total Alkalinity is in range. Once your TA is correct, you can then adjust your pH levels if needed.

What happens when you have low Total Alkalinity in hot tub?

Much like when you have low pH, your water will be more acidic, meaning you are at risk of damaging your hot tub and causing harm to yourself. Other effects of low TA are:

  • Irritation to eyes and skin
  • Corrosion to equipment such as pumps and seals
  • The sanitizer that you use (chlorine or bromine) will be less effective (especially chlorine), so more sanitizer will have to be used to maintain a correct pH
  • You will experience a pH bounce, meaning your pH will rise and fall rapidly and will be hard to maintain.

How to raise alkalinity in hot tub?

Just like with a low pH, you will use chemicals to increase the Total Alkalinity. Below is a recommended product to use, just make sure you follow the manufacturer's guidelines about how much to use.

SpaGuard Total Alkalinity Increaser

This total alkalinity increaser is simple and effective. Simply add 1 tbs per 100 gallons of water to bring your total alkalinity reading by 25ppm to leave your water looking fresh.

Buy on Amazon

Hot tub alkalinity too high? What Happens in the hot tub?

High Total Alkalinity is not as damaging as low TA, however, you still want to avoid it at all costs as it will have negative effects on your hot tub. When you have a high TA; you can expect:

  • Cloudy or murky water
  • Scale build up in the water and on equipment
  • Clogged pipes and filters, meaning the pump will have to work harder to maintain water flow and at the same time damaging the pump.
  • pH lock, which means that the pH is less resistant against pH adjusters, so you will have to use lots more chemical more frequently to achieve a correct pH range of your water.

How do you lower total alkalinity?

You need to purchase a Total Alkalinity decreaser to ensure that you can bring down the TA of your tub if you need to.

Always follow the manufacturer’s guidelines and apply as instructed.

Hot Tub Things pH & Alkalinity Down

This product will reduce your total alkalinity and pH together to help you maintain your hot tub’s water balance. Once your total alkalinity is in range, recheck your pH and then use a pH increaser if it is too low.

Buy on Amazon

Understanding & Controlling Calcium Hardness in Hot Tubs

The ideal range of Calcium Hardness is 150-250 ppm (parts per million).

Calcium hardness refers to the hardness and softness of your water. As with pH and Total Alkalinity, going higher or lower than the ideal range comes with problems.

Before you try to balance your Calcium Hardness, make sure that your Total Alkalinity is within ideal range (80-120 ppm), and the that your pH is within range (7.2-7.8).

What Does Low Calcium Hardness in hot tub do?

Water that is too soft, or has a low calcium hardness, is corrosive. The water effectively does not have all the minerals it needs, so to get its minerals it will take it from things it comes into contact with, namely your hot tub!

Low Calcium hardness is an issue with hot tubs that have metal, grouting, concrete or stone. As inflatable hot tubs only have metal out of these, then it will not be as damaging to the whole tub, but it will be enough to ruin your hot tub.

The water will corrode all the metal in your pump or any other metal that comes into contact with. Once this corrosion starts, it is not possible to reverse it. You will either have to buy a new hot tub or replacement parts.

How to raise Calcium Hardness in spa?

As with pH and Total Alkalinity, you need an increaser. You can purchase Calcium Hardness increaser and I recommend Leisure Time Calcium Booster below. As always, make sure to follow the manufacturer's instructions for use.

Leisure Time Calcium Booster

This high selling calcium booster will bring your calcium levels up at a rate of 7 ppm per dose. Compatible with chlorine and bromine sanitized spas.

Buy on Amazon

What Does High Calcium Hardness in hot tub do?

High calcium hardness means that the water has become saturated and the calcium is not being absorbed into the water. This results in cloudy water which over time will start to develop scale. As with high Total Alkalinity, the scale will cause the same damage, such as:

  • Blocking of filters
  • Blocking of lines and pipes
  • The pump being overworked which can lead to irreversible damage

How to lower the Calcium Hardness in hot tub?

Having a high Calcium Hardness means you have two options; partially replace some of the water with fresh water and failing that you will need to replace all the water in your tub with fresh water.

Summary and conclusions

To maintain your hot tub, you need to check the pH, total alkalinity, and calcium hardness regularly. Otherwise, any imbalance parameter will harm your skin and hot tub.

  1. You need Spa Test Strips to test all parameters.
  2. Check if alkalinity is in 80-120 ppm (parts per million). If not, use Total Alkalinity Increaser or Alkalinity Down to stabilize TA levels.
  3. Alkalinity in optimum range will make pH stable. Now check the pH. it should be between  7.2 & 7.8. If not, use Hot Tub pH Decreaser or Hot Tub ph increaser
  4. After pH and alkalinity are in range, you should check the calcium hardness. You can use Calcium Booster to increase CH or change water to lower it.

That's all! you have all needed information about chemicals to be used in hot tubs. Share this post with your readers, friends and social circle.



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