How To Raise the Alkalinity in a Hot Tub

As an online spa parts and chemicals distributor, we field a number of questions from customers that pertain to hot tub chemistry. One of these is, "How do you raise the alkalinity in a hot tub?"

pH Levels and Total Alkalinity

Before we dive into this topic, there is one thing we need to clear up: total alkalinity and pH, while connected, are actually two very different things. Because we describe water that is basic (opposite of acidic) as being "alkaline," it’s easy to see how these terms are so often confused — even among those in the industry!. But, to put it simply, pH is a relative measure of a solution's alkalinity as it relates to water, while total alkalinity (TA) measures the total number of alkaloids within a solution's sampled volume.

Understanding pH Levels

So, what is pH? The shorthand “pH” translates to the “power of hydrogen," which is a way of measuring the concentration of hydrogen ions within a given solution. This is the real measure of pH. But, when we are talking about how basic or acidic a solution is, we are looking at how a solution relates to pure water, which is at 7 on the pH scale. The numerical designations assigned to basic and acidic solutions aren’t arbitrary; each whole number interval within a pH scale is ten times more basic or acidic than the number it precedes. For example, a mixture with a pH of 8 would be 10 times more basic than a pH of 7, and a 9 pH would signify a solution that is 10 times more basic than a pH of 8, meaning it is 100 times more basic than pure water.

What is Total Alkalinity?

Total alkalinity is different from pH levels in that total alkalinity isn't a relative measure, but a measure of all alkaline chemicals dissolved in a sample (such as water). As it pertains to your hot tub's water, total alkalinity will typically signify the concentration of hydroxides, carbonates, bicarbonates, and other alkaloids within your sample. Total alkalinity is measured differently than pH ranges; total alkalinity is measured in parts per million (ppm), unlike the relative pH ratings.

Now, when you have a higher concentration of alkaloids your hot tub's pH becomes more stable since it would require more of a given substance to change its concentration of alkaloids. Based on these concepts, it is entirely possible to have a tub's water be pH balanced while still having issues with alkalinity.

How to Raise and Lower Alkalinity in a Hot Tub

Raising and lowering the alkalinity in a hot tub is something you need to be cognisant of when owning a hot tub. There are two ways to increase your hot tub's alkalinity level: sodium bicarbonate (baking soda) or any type of alkalinity increaser product.

Low total alkalinity is bad for your hot tub's various components (and more typical), as the surface of the shell can become etched, pitted, and even the protecting layer of the shell can delaminate. Any part made out of metal that comes into contact with water that has low total alkalinity can corrode, putting your heating elements, pipes, and heaters at risk. Calcium scaling can also occur, making it more difficult to keep surfaces clean and plumbing free of scale buildup. Therefore, you need to raise the alkalinity using a product such as SpaBoss Alka-Rise.

Raising a low alkalinity hot tub isn't the same as making it more basic or less acidic; what we're talking about is increasing the total concentration of alkaloids within the water. The most common types of alkaloids in hot tub water are carbonates, bicarbonates, hydroxides, and other minor alkaloids. These alkaline substances buffer pH in the water by neutralizing acids. In other words, total alkalinity is a measurement of the water’s ability to resist change in pH. Alkalinity increasers are products designed to increase the total concentration of alkaloids in hot tub water.

On the other side of the coin, hot tubs can have high alkalinity due to too many chemicals, sweat, lotions, your water source, or simple human error! If it's too high, it can render your sanitizing agent and cause green water and bacteria to grow. If too high, the easiest way to lower the alkalinity is by using a pH Decreaser (sodium bisulfate).

Here's how to fix alkalinity levels in a hot tub:

Turn off the jets to your hot tub.
Take a water test strips.
Add baking soda or another alkalinity increaser such as SpaBoss Alka Rise to RAISE alkalinity.
Add a pH Decreaser (sodium bisulfate) such as SpaBoss pH Minus if alkalinity is HIGH in order to lower alkalinity.
Retest water after 24 hours and re-adjust levels from there.

How to Test and Raise Alkalinity Naturally

So, what if you want to test and raise alkalinity levels in a hot tub the natural way? That makes sense and it's a good notion - as sometimes that harsh liquids or dry chemicals can be damaging!

Here's how:

Turn off your spa jets
Look for the pH level of water by using a water test strip
Add 1 table of baking soda to your spa (per 100 gallons of water it holds- check the manual to be sure.)
Turn your spa jets back on and have the water circulate
Check and retest pH level of water 3-4 hours later. If level is still low, add more baking soda and repeat above steps.

Our Favorite Alkalinity Increaser

At Master Spa Parts, we offer an assortment of products from SpaBoss, including the SpaBoss Alka Rise. SpaBoss products are designed for those looking to achieve the right hot tub chemical concentrations (no chemistry degree required). An alkalinity increaser such as the SpaBoss Alka Rise helps to prevent pH fluctuations that can damage your hot tub's moving parts (plumbing, jets, pumps, etc.) and also corrode metallic materials.

A well-balanced alkalinity in your hot tub is an essential part of creating a safe, healthy hot tub environment. It's nearly impossible to enjoy a hot tub that is cloudy, irritating to the skin, eyes, or throat. If your tests indicate that an alkalinity increaser should be used, this is definitely a step you do not want to skip. Also, if you happen to be using a bromine-based disinfectant system, then your hot tub's total alkalinity can decline faster than granular chlorine-based systems.

Have a Question?

If you've read through this article and you're still trying to make sense out of the whole raising total alkalinity concept, just drop us a line. Master Spa Parts' specialists are always happy to answer customer questions.

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