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Mastering Hot Tub Alkalinity

Mastering Hot Tub Alkalinity

If you are new to hot tubbing, you may have thought Alkalinity and pH were the same and not something to worry about. Other hot tubbers like yourself may not be sure about the difference.  This article will explore this pillar of water chemistry and how to correct it when things go wrong.

As you read through, I will answer these essential questions about hot tub alkalinity.

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What is Alkalinity

Let’s start with what Alkalinity is. Alkalinity is the presence of calcium, magnesium, and other compounds in your water that act as a buffer against swings in your pH level. It works to hold your pH levels in place so it remains balanced, preventing rapid swings in your water chemistry. Think of it as your first line of defense for maintaining healthy, clear water.

Testing for Alkalinity

When you test Alkalinity and the difference from what pH is. With Alkalinity, you are measuring your water’s capacity to prevent pH from drifting up or down. On the flip side, when testing your pH, you measure how acidic or basic your water is. So, to recap, Alkalinity comprises minerals that prevent pH from getting out of control.

Where should it be? The recommended alkalinity range for hot tub water is between 80 ppm and 120 ppm or parts per million. You can quickly test this at home using a reliable water testing kit or test strips. Beginners should test your water once a week. Once you get this down, skip a week and test your water twice a month if you use your hot tub regularly.

Why Alkalinity is So Important

My preference when testing water is what we call a drop kit. It uses reactive drops to measure your levels. I think the colors are much easier to read, and the color won’t change over time during the test as a strip does. If you prefer one-on-one advice, I recommend taking a cup-sized water sample to your local hot tub store, and they can check it for you.

Can Alkalinity Damage my Hot Tub

You might be asking what happens if you ignore your alkalinity levels when your alkalinity dips below 80 ppm.

This can lead to a host of issues, including:

  • Corrosion of your EquipmentEtching and staining of your equipment surfaces.
  • Uncomfortable burning or itching of your eyes and skin.
  • Your water takes on an unsightly green hue and can be confused with algae growth.
  • And, of course, Wild pH fluctuations.

Going the other way, if your alkalinity climbs above 120 ppm.

This can result in:

  • Your Equipment scaling and potentially being damaged.
  • As in Low Alkalinity, discomfort from burning or itching of the eyes and skin.
  • Your water turns cloudy and unappealing to soak in.
  • Also, when pH becomes Elevated, it is harder to lower the alkalinity.

What Effects Alkalinity

What causes alkalinity fluctuations in your hot tub water? They can range from natural environmental influences like rain and other debris falling into your hot tub to bodily reactions of everyday products applied to your skin and hair. Even regular chemical treatments can have a plus or minus effect on alkalinity.

Let's dive in a little deeper into the causes of those highs and lows and how to fix them.

High Alkalinity

When you have high Alkalinity, the number one reason for this is using a water source that already has high alkalinity. Second is body oils and lotions introduced into the water while soaking in your hot tub. Another cause is going overboard with calcium-based chlorine that pushes your alkalinity upwards. The fourth one I learned while researching this article. As your water naturally evaporates, the minerals and other alkaline compounds in the water become more concentrated, leading to higher alkalinity levels.

Before discussing fixing your alkalinity, the first question you should ask yourself is how old the water is. If it is over four months old, it’s like expired milk. Dump it and start over!

When fixing high alkalinity, you have two options: one is Muriatic Acid, which is a liquid, and the other is Sodium Bisulfate, also known as pH down or decrease. It is available in both liquid and granular powder.  

Your first choice would be the Sodium Bisulfate (pH down).  Since a hot hot tub is a small body of water, this is a better option to adjust alkalinity.  If your pH falls out of the 7.2 ppm to 7.8 ppm range. You can adjust it after you lock in your alkalinity.

The use of pH down is because, as you may have inferred, alkalinity and pH are tied together, so often, when you adjust one, you impact the other, and the next option is not as desirable.

Muriatic Acid, proceed with caution. This should only be used with extremely poor water conditions, as with some types of well water. While effective, it does require careful handling due to its caustic nature. Ensure to follow the instructions on the bottle or consult your local hot tub professional for proper use, even though it requires extra care. Instead, I recommend a trucked-in water source to fill your hot tub.

Low Alkalinity

Now, what decreases your alkalinity? Like in low alkalinity, your water source or rain can be the issue. Also, using chemicals like chlorine or bromine in your hot tub can cause reactions that gradually lower alkalinity over time.

Even certain types of microbial activity in your water, while unpleasant to think about, can consume alkaline compounds as part of their diet. In addition to all of that, acidic oils and lotions can also alter your water chemistry and decrease alkalinity levels.

To raise your alkalinity back up, you would use ordinary Baking Soda, which is Sodium Bicarbonate. As in lowering alkalinity, this will also have a small impact on pH levels since alkalinity and pH are interconnected.

When making any adjustments, I suggest doing them gradually. It’s better to do small doses rather than attempting a significant adjustment and overshooting the mark.

Keeping your alkalinity levels in check ensures a more enjoyable hot tub experience and adds to the longevity of your beloved hot tub and its components.

In Conclusion

Understanding and maintaining proper alkalinity levels in your hot tub is crucial for a hassle-free and enjoyable soaking experience. Alkalinity is a buffer against pH fluctuations, safeguarding your hot tub from issues such as corrosion, scaling, and discomfort. Regular testing and adjustment within the recommended range of 80 to 120 parts per million (ppm) are essential to prevent potential problems. Whether dealing with high or low alkalinity, the key lies in using appropriate chemicals like Sodium Bisulfate or Baking Soda, applied gradually to avoid overcorrection. Ignoring alkalinity can lead to equipment damage, skin irritation, and water quality issues. By prioritizing this aspect of water chemistry, you not only enhance the longevity of your hot tub but also ensure a consistently pleasant and safe environment for relaxation.

Next Steps

  1. Regular Testing: Make it a habit to test your hot tub water regularly, especially if you are a beginner. Use a reliable water testing kit or test strips to measure alkalinity levels. Aim to test once a week initially and adjust the frequency based on your hot tub usage.
  2. Choose the Right Testing Method: Consider using a drop kit for testing alkalinity as it provides more accurate and consistent results compared to test strips. Alternatively, local hot tub stores can offer professional testing services if you prefer one-on-one guidance.
  3. Maintain Alkalinity Levels: Keep your hot tub’s alkalinity within the recommended range of 80 to 120 ppm. This helps prevent issues such as corrosion, scaling, and uncomfortable pH fluctuations. Regular maintenance contributes to a clear, balanced, and inviting hot tub environment.
  4. Addressing High Alkalinity: If your alkalinity levels are high, consider using Sodium Bisulfate (pH down) to gradually adjust it. Take extra care when using Muriatic Acid, reserving it for extreme cases. If your water is over four months old, it might be time for a complete water change.
  5. Dealing with Low Alkalinity: Low alkalinity can be corrected using ordinary Baking Soda (Sodium Bicarbonate). Remember that adjustments should be made gradually to avoid overshooting the desired levels. Factors such as rain, water source, and chemical use can influence alkalinity, so monitor these closely.
  6. Prioritize Gradual Adjustments: Whether you are increasing or decreasing alkalinity, opt for gradual adjustments. Small, incremental changes are preferable to prevent unintended consequences and to achieve a more controlled outcome.
    Overall Hot Tub Maintenance: Keeping alkalinity in check is just one aspect of maintaining a healthy hot tub. Regularly clean your hot tub, change water filters, and follow manufacturer guidelines for optimal care.
  7. Seek Professional Advice: If you encounter challenges or uncertainties in managing your hot tub’s alkalinity, don’t hesitate to consult with local hot tub professionals or seek advice from reputable sources. They can provide tailored guidance based on your specific circumstances.

Suggested Products

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