How Much pH Increaser Should I Add to My Hot Tub?

pH increaser to add lg

If you’re trying to get the pH level correct in your hot tub and it’s too low, you’re naturally wondering “how much pH increaser should I add to my hot tub?”

Here’s what I do:

As a rule, to raise the pH by 0.1 to 0.2 ppm, add 0.16 ounces of pH increaser for every 100 gallons of water, so a 500-gallon tub will need around 1 ounce (2 tablespoons) to go from 6.8 to 7.2.

Ultimately, it’s always better to add less. You can always add more, but if you overdo it, you’ll just have to wait or add a pH decreaser.

But there’s more to know than just that.

So in this article, we’ll explore that further, look at the dangers of soaking in high or low pH, talk about how long to wait before it’s safe to get in after adding chemicals, and we’ll look at what to balance first; alkalinity or pH.

Let’s get started.

Ready to Spend Less Time On Maintenance and More Time Enjoying Your Hot Tub?

Let’s face it. Balancing the water, cleaning filters, dealing with rashes, and trying to figure out which chemicals to buy and add can make you feel more like a chemist than someone who just wants to relax after a long hard day!

That’s exactly why The Hot Tub Handbook and Video Course is so valuable!

This is from Matt over at Swim University and he developed it for people looking to save money, time, and frustration. His tips on chemicals can save you $100/year just by making sure you buy only what you need.

So if you’re ready to stop being confused or frustrated with your hot tub and start spending more time in it, check out The Hot Tub Handbook and Video Course.

Just click that link to learn more on their website.

What happens if you put too much pH increaser in a hot tub?

Too much pH increaser in a hot tub can cause itchy skin and burning eyes. And it can cause an increase in scale buildup which shortens the lifespan of the equipment.

So if you’ve overdone it, the best solution is to use a pH reducer to bring the levels back down.

You should test your hot tub water at least twice a week, more after heavy usage, using test strips. You can get these from your local dealer, but the type I recommend is the Poolmaster 6-Way test strips on Amazon. Just click on the link to check the latest prices.

But the best way to avoid too much is to add it in small amounts.

If you add too much and the pH level exceeds 7.8 ppm, you shouldn’t go in the water! How bad is it to get in high pH water? You can see more on this in a recent article. Aside from red skin and itchy eyes, there’s 1 additional thing that might require medical treatment!

Just click on the link to read it on my site.

So start small. Turn on the jets and leave the cover off, and then test again in 20 minutes. You can always add more; you can’t add less.

What should be adjusted first, alkalinity or pH?

Always adjust the alkalinity first before pH. If the alkalinity is not correct, it can become impossible to balance the pH as the water’s ability to neutralize acid will be compromised.

But what’s the difference, and how do they relate to each other?

Many people get confused about pH and alkalinity, which is why I wrote about it in a recent article. But essentially, alkalinity measures how well the water is able to neutralize the acid. So if it can’t neutralize it, your pH will always be too low.

Alkalinity acts as a buffer to prevent the pH from shooting up or down as chemicals are added.

Ideally, alkalinity should fall between 80 and 120 ppm. If it is too low, it will fail to control the pH, and the sanitizing effect of the chlorine or bromine will be compromised. Too high, and the pH level will rise, causing cloudiness.

To raise alkalinity, you should add sodium bicarbonate, and to lower it, add something acidic such as sodium bisulfate. 

Leisure Time on Amazon has a range of products that make this simple if you don’t like all these chemical names.

With names such as ‘Alkalinity Increaser’, ‘Spa Up’, and ‘Spa Down’, it’s easy to get the right product for your needs. Just check out their details and get the latest prices on Amazon by clicking on the links.

How long does pH Up take to work in a hot tub?

pH up or spa up products typically work in approximately 20 minutes. Add a small amount of product, leave the cover off, turn on the jets and water features, circulate and test 20 minutes later.

Adjust as needed and then wait again if more product was added.

The term pH Up refers to products that are added to the water to raise the pH level, helping it become less acidic. Many commercial products contain potassium hydroxide and potassium carbonate, but others are just pure sodium bicarbonate (baking soda).

While baking soda works well as a pH up, sodium carbonate (soda ash) is better.

Any pH increaser will get to work straight away, but you should wait 20 minutes after adding it before testing again. If it is still out of range, add a little more, then test again after 20 minutes. Keep doing this until it is in range.

You must add chemicals in small doses to avoid overdoing it, and the key to that is knowing how much you need to add to the water, to begin with.

The first thing you need to know is the volume of water in your tub.

Don’t just rely on the manufacturer’s quoted size, try measuring it yourself – while the length of the sides is constant, the depth will vary. In a recent article, I explained in more detail how to work out the volume with a really simple formula.

Just click on the link to see it here on my website.

Is it safe to get in a hot tub with low pH?

If the pH level in a hot tub is below 7.2, it will be acidic and is unsafe to get in. Being acidic can lead to burning skin and irritated eyes. It can also corrode any metal pipes and the pump, so it must be addressed immediately.

The lower the value, the more acidic it is.

Low pH usually leads to cloudy water and a pungent smell, although this isn’t always the case, so be sure to test the level frequently. I test mine weekly. Luckily, once correctly balanced, the pH and alkalinity rarely drift in large amounts until the next water change.

But if you see the pH drifting frequently, you need to know is what is causing the pH level to drop.

The most common cause of any chemical imbalance is a biofilm, which is caused by things like body lotions, perfume, bodily fluids, hair, and dead skin. You must add a sanitizer such as chlorine to the water regularly to kill off the bacteria that thrive in these conditions.

But if the biofilm buildup is bad, chlorine alone won’t get rid of it.

In that case, the best strategy is to use Oh Yuk! Healthy Hot Tub Cleaner from Amazon and then change the water after using it. I do this every time I change the water in my hot tub (about every 3 months).

Another cause of low pH after a refill is the water supply you use to fill your hot tub.

Hard water is high in minerals, and this gives it a high pH, but soft water is low in pH. If you have a water softener fitted, it is best to disconnect this before filling your hot tub.

Low pH means that the sanitizer will work less efficiently, adding to the problem even more.

Can you go in a hot tub after adding pH increaser?

As a general rule, it is ideal to wait 20 minutes after adding pH increaser. This is not because pH increaser is dangerous, but it’s best to wait and test the water again to ensure the pH is correctly balanced.

And you won’t get an accurate reading until the chemical has been circulating for at least 20 minutes.

Soda ash (sodium carbonate) is the best product to use to raise the pH level, but it will also raise the alkalinity. If you want to raise the pH without significantly impacting total alkalinity, you should use this magnesium oxide powder from Amazon.

Most people will know of this as a food supplement beneficial for bones and teeth, but it is also a great product to have around for use in your hot tub.

So add a little bit, wait 20 minutes and then test again. If the levels are good, then dive on in!

If you add too much pH increaser, so the level is above 7.8 ppm, you will need to add a decreaser to bring it back down again. You can see now why it is important to add chemicals in small doses, test, and repeat until you get it right.

Always test the water before you get in if you are having problems balancing pH and alkalinity.

Final Thoughts

The main thing is knowing how much to add depending on the volume of water and pH level. Then, you should add just the right amount to bring the level back in the range of 7.2 to 7.8.

Once you get that right, you’re good to go.

I hope this gives you the information you need to balance the pH level in your hot tub. If you need any more advice, just reach out to me – I’d be glad to help.

And don’t forget to click on those links to read other associated articles here on my site.

Ready to Spend Less Time On Maintenance and More Time Enjoying Your Hot Tub?

Let’s face it. Balancing the water, cleaning filters, dealing with rashes, and trying to figure out which chemicals to buy and add can make you feel more like a chemist than someone who just wants to relax after a long hard day!

That’s exactly why The Hot Tub Handbook and Video Course is so valuable!

This is from Matt over at Swim University and he developed it for people looking to save money, time, and frustration. His tips on chemicals can save you $100/year just by making sure you buy only what you need.

So if you’re ready to stop being confused or frustrated with your hot tub and start spending more time in it, check out The Hot Tub Handbook and Video Course.

Just click that link to learn more on their website.


Photo which requires attribution:

Still frame taken from video How to Add Hot Tub Chemicals to your Hot Spring spa by The Hot Tub Store is licensed under CC2.0 and was cropped, edited, and had a text overlay added.

Jeff Campbell

Jeff Campbell is a husband, father, martial artist, budget-master, Disney-addict, musician, hot tub lover, and recovering foodie having spent over 2 decades as a leader for Whole Foods Market.

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