Maintaining the correct water chemistry in your hot tub is essential for both comfort and safety. One key aspect of this is ensuring the right alkalinity level. Low alkalinity can lead to fluctuating pH levels, causing damage to hot tub components and irritation to the skin and eyes. To enjoy a relaxing and safe soak, you need to know how to increase alkalinity in your hot tub efficiently and correctly. The following information will guide you step-by-step through understanding, testing, and raising alkalinity levels in your spa.
Understanding Alkalinity in a Hot Tub
What Is Total Alkalinity?
Total alkalinity refers to the water’s ability to buffer pH changes. Essentially, it keeps the pH level stable. When alkalinity is too low, pH becomes volatile and can swing drastically, leading to uncomfortable water conditions and potential corrosion of your hot tub’s internal systems.
Ideal Alkalinity Range
For hot tubs, the ideal total alkalinity range is typically between 80 and 120 parts per million (ppm). Staying within this range helps to maintain a balanced pH, reduce scaling or corrosion, and provide a more enjoyable bathing experience.
Common Causes of Low Alkalinity
There are several reasons why your hot tub’s alkalinity might drop below the recommended range:
- Frequent refilling with soft or acidic water
- Excessive use of chlorine or bromine sanitizers
- Rainwater dilution after an outdoor tub is left uncovered
- Overuse of pH-lowering chemicals
Understanding the cause is key to preventing future drops in alkalinity.
How to Test Alkalinity
Use Test Strips or Liquid Kits
You can test your hot tub’s alkalinity using test strips or liquid test kits. Both are available at pool and spa supply stores. Follow the instructions closely, making sure to dip the strip or take the water sample from about elbow depth for accurate readings.
When to Test
It’s best to test alkalinity at least once a week, and especially after heavy use, refilling the tub, or adding large amounts of chemicals. Regular testing allows you to catch imbalances early before they become bigger problems.
Steps to Increase Alkalinity in a Hot Tub
1. Choose the Right Chemical
To raise total alkalinity, you’ll need an alkalinity increaser. The most common product used is sodium bicarbonate baking soda. Commercial spa alkalinity increasers are usually composed of the same substance but may include additives to help with dissolving and effectiveness.
2. Calculate the Required Amount
As a general guideline, 1 tablespoon of sodium bicarbonate per 100 gallons of water can raise alkalinity by approximately 10 ppm. Use this to estimate how much you need based on your hot tub’s size and the current test results.
3. Turn On the Circulation
Before adding any chemicals, turn on the hot tub’s circulation system. This helps distribute the chemical evenly throughout the water and prevents concentrated spots.
4. Add the Alkalinity Increaser
Sprinkle the baking soda or commercial alkalinity increaser across the surface of the water while the jets are running. Do not dump it all in one place, as this may lead to uneven chemical distribution.
5. Wait and Retest
Allow the water to circulate for at least 24 hours. Then, retest the water’s alkalinity. If it is still below the desired level, repeat the process in small increments to avoid overcorrection.
Balancing Alkalinity and pH
Why You Should Adjust Alkalinity First
Always adjust alkalinity before pH. Because alkalinity acts as a pH buffer, raising it will often raise the pH slightly as well. This interconnected relationship means that trying to balance pH before fixing alkalinity can result in a cycle of continual adjustments.
Dealing with High pH After Raising Alkalinity
If your pH level becomes too high after increasing alkalinity, use a pH reducer (typically sodium bisulfate) to bring it back down. Again, make adjustments slowly and test frequently.
Tips for Maintaining Balanced Water
- Cover your hot tub when not in use to prevent debris and rainwater from altering the water chemistry.
- Shower before entering the hot tub to reduce contamination from body oils and lotions.
- Use a reliable testing method regularly to monitor pH and alkalinity levels.
- Maintain your filtration system and clean it as recommended by the manufacturer.
Regular Maintenance Goes a Long Way
Preventing alkalinity imbalances is easier than fixing them. By incorporating a weekly testing routine and adjusting chemical levels as needed, you can avoid common hot tub water problems and ensure a clean, safe soak every time.
What Happens If Alkalinity Remains Too Low?
Persistent low alkalinity can lead to a number of serious issues:
- Corrosion of metal parts such as heaters, pumps, and jets
- Etching of acrylic or plaster surfaces
- Unstable and fluctuating pH levels
- Skin and eye irritation for users
Addressing low alkalinity promptly helps preserve the life of your hot tub and ensures it remains a source of enjoyment instead of frustration.
Natural Methods for Alkalinity Adjustment
While chemical solutions are the most reliable, some hot tub owners prefer more natural or gentle options. Baking soda, which is both affordable and effective, remains the best natural solution. However, always test the water thoroughly, even with natural remedies, to avoid overcompensating.
Avoid Vinegar or Acidic Additives
Some DIY sources suggest using vinegar or lemon juice to lower pH or alkalinity. While these are acidic, they are not stable solutions and can cause erratic water conditions. Stick with tested spa-grade chemicals for more predictable and safe results.
Learning how to increase alkalinity in a hot tub is an important part of responsible spa ownership. With the right tools, regular testing, and a little know-how, maintaining balanced water becomes a simple part of your routine. A well-balanced hot tub doesn’t just extend the life of your equipment it ensures that every soak is comfortable, clean, and refreshing.