Maintaining the perfect balance in your hot tub water is crucial for a relaxing and safe soaking experience. One key element of this balance is alkalinity, which refers to the concentration of alkaline substances (primarily bicarbonates) in your hot tub water. High alkalinity can lead to several problems, including cloudy water, scaling, and reduced effectiveness of sanitizers.
Understanding Alkalinity and pH
Before diving into how to lower alkalinity, it’s important to understand the difference between pH and alkalinity.
- pH (Potential of Hydrogen): This is the measurement of how acidic or basic your hot tub water is. The ideal range is between 7.2 and 7.8 (some sources say 7.4 and 7.6).
- Alkalinity (Total Alkalinity or TA): This refers to water’s ability to neutralize acidic changes in pH. It is the capacity of water to resist acidification, often referred to as the ‘buffering capacity’ of a solution. Total alkalinity is measured in parts per million (ppm), and the recommended range for hot tubs is typically between 80-120 ppm, though some recommend keeping it between 100-150 ppm to allow for more fluctuation.
pH is volatile, meaning any little thing that interacts with your water can cause drastic pH fluctuations. Alkalinity, on the other hand, helps maintain pH balance. Without alkalinity, your water’s ability to maintain pH balance would be all over the place.
Why is High Alkalinity a Problem?
High alkalinity can cause several issues in your hot tub:
- Cloudy Water: High alkalinity may manifest as greenish or cloudy water.
- Scaling: Mineral deposits can form on the surfaces of your hot tub, leading to scaling.
- Reduced Sanitizer Effectiveness: High alkalinity levels can cause chlorine or bromine-based disinfectants to be ineffective, potentially leading to green water and bacteria growth, making the hot tub unsafe.
- Skin and Eye Irritation: High alkalinity can cause skin and eye irritation.
Causes of High Alkalinity
Several factors can contribute to high alkalinity in your hot tub:
- Too Many Chemicals: Adding too many chemicals to your hot tub can increase the Total Dissolved Solids (TDS), leading to high alkalinity.
- Body Oils and Lotions: Sweat, lotions, sunblocks, perfumes, hair gel, and other personal care products can raise the pH.
- Water Source: Your local water source may have a naturally high alkalinity reading. Contact your township, county, or local water district for a water reading. If your alkalinity is too high, it could be an issue of hard water in your area.
- Human Error: Accidentally adding too much Alkalinity Increaser or baking soda can increase alkalinity.
- Hard Water: If your alkalinity is too high, it could be an issue of hard water in your area.
How to Lower Alkalinity in Your Hot Tub
The easiest and most effective way to lower alkalinity in your hot tub is by adding a pH Decreaser (sodium bisulfate), also known as a pH reducer or pH minus. It's important to note that it is not possible to lower alkalinity without lowering pH. However, to overcome this, alkalinity and pH are both lowered and then the water is aerated to increase the pH level back to the ideal range.
Here's a step-by-step guide:
- Test Your Water: Begin by testing the water to determine the current alkalinity level. Dip a testing strip in the water and then shake off any excess water before comparing the color on the strip to the bottle chart on the back of the kit. For the most accurate water test, collect a water sample into a clean cup and test it after it has cooled to room temperature.
- Calculate Water Volume: Before adding any chemicals to your hot tub, you need to know how much water your hot tub holds.
- Choose the Right Chemical: To lower alkalinity effectively and safely, use a pH reducer (sodium bisulfate). Avoid using muriatic acid, which can be harsh on hot tubs.
- Determine the Dosage: Follow the instructions on the pH Decreaser product label to determine the correct dosage based on your hot tub's water volume and current alkalinity level. For example, if your hot tub has 1,000 gallons of water, use about 3 ounces (85 grams) of pH Decreaser to lower the alkalinity by 10 ppm.
- Dilute the pH Reducer: Always add the pH reducer to water, not water to the reducer.
- Add to Hot Tub: Slowly pour the diluted pH reducer into the hot tub water, preferably near a jet to help with circulation.
- Wait and Retest: Allow the water to circulate for at least one to two hours, then retest the alkalinity level.
- Adjust pH Levels: Lowering alkalinity can also lower the pH levels. After adjusting the alkalinity, check and adjust the pH to maintain it between 7.2 and 7.8. Aerate the water. Using your air jets or a built-in fountain will help control the pH without affecting the alkalinity reading.
Alternative Methods and Considerations
- Vinegar: While some sources suggest using distilled white vinegar to lower alkalinity, it’s generally not recommended for hot tubs. White vinegar (or any other type of vinegar) does not lower alkalinity effectively in hot tubs. Gather supplies. Find some distilled white vinegar or other acidic substance and measuring cup. Add vinegar to hot tub. Pour in ½ cup vinegar for every 100 gallons of water in the hot tub. Retest the water. Wait 24 hours, then retest the water.
- Aeration: Aeration creates turbulence, which causes carbon dioxide (CO2) to outgas and increase the pH. Aeration is the only way to increase pH without increasing total alkalinity. So, the key is to increase the surface area of the pool as much as possible. The easiest way to do this is to turn the pool return system on full, towards the surface of the water, and also to blast the pool pump at full capacity. This forces disruption on the water’s surface.
- Professional Advice: If tests and treatments don’t take care of the issue, it’s time to try testing pH levels to find out how acidic or basic your water is.
What Not to Do
- Baking Soda: Do not use baking soda to lower alkalinity; baking soda raises alkalinity because the main active ingredient is sodium bicarbonate.
- Waiting: If your alkalinity is high, don’t wait to address it.
- Soaking: While soaking in high alkalinity water won’t necessarily harm you, it can be uncomfortable on your skin, so it’s best to avoid soaking in hot tub water with a high alkalinity reading.
- Adding to a Pool: While we sometimes recommend adding it to a pool, it’s too much to add to a hot tub.
Preventing High Alkalinity
- Regular Testing: Regularly test your hot tub water to monitor alkalinity and pH levels.
- Careful Chemical Addition: Be precise when adding chemicals to your hot tub to avoid over-treating the water.
- Cleanliness: Encourage users to shower before entering the hot tub to minimize the introduction of body oils, lotions, and other contaminants.
- Water Source Awareness: Be aware of the alkalinity levels in your local water source and adjust your chemical treatments accordingly.
Lowering Alkalinity in Other Applications
The principles of lowering alkalinity can also be applied to other situations, such as in aquariums and soil.
Aquariums
Aquariums that have high alkalinity levels pose a threat to fish. Alkaline waters can cause ammonia spikes, which are toxic to aquarium life and are linked to breathing issues with fish.
- Dilution: The best way to lower alkalinity in aquariums is to dilute the water with purified water that has a low-mineral content, such as through reverse osmosis.
- CO2 Addition: Another method is to add CO2.
- Natural Components: A preferred method is to add peat moss, driftwood, or Indian almond leaves, which absorb alkaline elements in the aquarium water, lowering the alkalinity and pH.
- Remove Calcium-Rich Materials: Remove calcium-rich stones and rocks that contain limestone or crushed shells that have a high calcium compound.
- Algae Reactors or CO2 Scrubbers: Add algae reactors to absorb CO2 or a CO2 scrubber to help maintain alkalinity levels.
Soil
Poor alkalinity levels and low pH impair plant growth by preventing water from reaching the roots, stunting growth, and reducing root development. Alkaline soils have a pH value of 8.5 to 10.0 and are usually from over-liming acidic soils and alkaline irrigation waters.
- Chemical Methods:
- Gypsum: If soils don’t have a reserve of calcium carbonate, applying gypsum is essential to lower alkalinity in the soil.
- Sulfur: If the soil contains free calcium carbonates, sulfur is added to lower the soil’s alkalinity.
- Organic Matter: Add organic matter to soils to lower the alkalinity over time, increase microbial life, and improve the soil structure. The addition of molasses provides energy for soil fermentation to occur and produce organic acid to reduce alkalinity.
- Cultural Methods:
- Proper Drainage: Artificial drains can be used to lower the alkalinity in the soil if proper drainage is not available.
- Proper Irrigation Water: Keep the soil moist at all times.