how to lower alkalinity in a hot tub

One major concept to understand when you’re new to hot tub ownership is how to monitor the chemical composition so that it doesn’t get out of whack. Learning how to increase and decrease the total alkalinity in your hot tub’s water is important. Maintaining the correct balance is crucial for your skin and hair.

The good thing is, you’ve come to the right place.

Continue reading as we make raising and lowering hot tub alkalinity easy!

Is High Alkalinity In A Hot Tub Bad?

If your total alkalinity in your hot tub water is far too high, the ph level of your hot tub’s water can become imbalanced.

In the end, you can end up with high and calcium levels in your hot tub water. The consequences of this much calcium can include cloudy water, scaling, and filter clogging.

Is Low Alkalinity In A Hot Tub Bad?

So, should I worry about low alkalinity?

Just because you don’t want your hot tub’s alkalinity level too high does not mean that you want to have it too low either. Hot tub water with extremely low alkalinity levels can end up being corrosive. When exposed to metal, low alkalinity water levels will begin to attack your jets and other parts of your system.

As time goes on, your hot tub may become damaged.

Hot tub owners take note: this is very important to avoid if you want to enjoy your hot tub for many years down the line.

Baking soda in hot tubs works really well to raise the total alkalinity of the hot tub water.

Understanding Alkalinity and ph

Prior to discussing how we can reduce the alkalinity in the hot tub, it is crucial that we make sure that you understand what you need to do and why you need to do it.

We promise that we will try to make this as simple as we possibly can.

The ph level is a measurement of how basic or acidic a given solution is. If a hot tub’s ph level is greater than 7, we would call it acidic. 

If it has a high ph level that is above 7, we would call it basic.

Anything that sits in the middle at a 7 ph level is considered neutral.

Coffee, for example, sits at a ph level that is somewhere around 5-6, meaning that it is just slightly acidic. Going further into acidity is lemon juice, which sits at a ph level that is anywhere from 2-3.

Moving towards the other end of the spectrum, we have things like bleach, which sits at a ph level of 13. So yes, bleach is one of the most basic things around.

There is often quite a bit of confusion when it comes to ph and alkalinity. ph and alkalinity are two very different things, even though many people believe that they are the same.

Yes, we might be able to conclude that your spa water is basic if it has ph levels that are above 7, though that doesn’t have anything to do with the alkalinity.

When we talk about alkalinity levels, we talk about the amount of acid it is able to neutralize.

When we dissolve an alkali in your hot tub’s water, it is able to neutralize any existing acid. When we talk about total alkalinity, we mean how much of your alkaline substance you have dissolved in your hot tub’s water. We measure total alkalinity in parts per million.

In an ideal world, your hot tub’s water should have anywhere from 80 to 120 parts per million total alkalinity.

A hot tub that has the proper total alkalinity is much better off when it comes to counteracting ph level changes and resisting any of the unwanted changes that we spoke about above. Getting the right ph alkalinity is extremely important for this reason.

So yes, your hot tub’s total alkalinity and ph might be somewhat related, though these two things are completely different.

Click here if you’d like to find out what causes high ph in a hot tub.

How To Test Your Hot Tub’s Total Alkalinity

One of the first things that you need to do when attempting to adjust your spa’s total alkalinity is to test it out using a test strip. Test strips are pretty easy to find in most pool and hot tub stores.

Typically, these test strips will come with clear directions on how to apply them, which you should follow to a tee.

Like we said before, the total alkalinity in your spa should be somewhere between 80ppm and 120 ppm. However, even if you measure the total alkalinity in your hot tub and it looks perfect, it is still very important that you check it multiple times per week, as the total alkalinity has the ability to change pretty quickly.

Checking your alkalinity and ph levels in your hot tub is one of the most basic parts of owning a hot tub.

The same thing goes if you are the owner of an inflatable spa.

How To Lower The Alkalinity In Hot Tubs

If you notice that your spa’s alkalinity is more than 120 ppm, then you will need to reduce it. One of the easiest ways to reduce the alkalinity in your spa is to put in something called sodium bisulfate.

Before adding your sodium bisulfate, you must decide how much you should add. The amount of sodium bisulfate that you end up adding will have to do with your hot tub’s volume. You also need to consider how much of the total alkalinity in your tub that you have to reduce.

Luckily, this is a pretty easy equation to work out.

For example, if you want to lower the alkalinity level of a hot tub by 10ppm and that hot tub has 1,000 gallons, you must add sodium bisulfate in 3.5 oz instances. You can double or half that amount depending on the number of gallons in your hot tub.

Once you know how much sodium bisulfate you should put in your hot tub, set it so that it is circulating and leave it going for about 20 minutes before shutting the circulation off.

When the water stops moving, walk away from your hot tub for about an hour before coming back and using a test strip to test it out again. This will tell you whether or not your alkalinity must still be lowered.

Once the proper alkalinity has been reached, you should leave your hot tub overnight before testing it again in the morning to make sure that it is still sitting at the proper level.

How To Increase Alkalinity In Hot Tub

If you put in a bit too much of your sodium bisulfate before noticing your alkalinity level drops too low, then you might have to raise it.

The procedure for raising the alkalinity in a spa and getting it to the ideal range is pretty similar to lowering it.

When it comes to raising the level, you will need to use something called sodium bicarbonate. 

The dose of sodium bicarbonate is 2.25 oz per 1,000 gallons in order to raise it by 10 parts per million.

While the hot tub water is in circulation, add your chemicals and allow the water to circulate for at least 20 minutes. Once you’re done, step away from your hot tub for about an hour before coming back to test it again. If you still need to raise your alkaline levels when you return, you can add more of your increaser.

When your water gets to the proper alkalinity level, leave your hot tub overnight and return in the morning to retest it once more.

Retesting Your Water’s ph

Once your alkalinity level gets to the desired range, you need to test your water’s ph once again. Any time that you make adjustments to the alkalinity in your spa, it will likely alter the hot tub’s ph. If you notice that you have a low ph, you will need to use some sort of dedicated product to raise ph levels.

There are many products to determine where on the ph scale your water sits.

If you’re interested in a more natural way to treat water in hot tubs, check out our article below:

Natural Hot Tub Treatment Reviews

Final Thoughts – Monitoring Your Water

Hot tub water care and hot tub maintenance are essential parts of owning hot tubs. Getting your alkalinity levels right is one of the most important parts of this water care.

You want to make sure that the chemistry in your water is correct. If not, you could damage your hot tub. The last thing you want to do is allow your system to get out of whack. Create a schedule for balancing your water and keeping it in the proper range so that you can stay free from spa problems.

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