Few things rival the pleasure of unwinding in your hot tub after a demanding day. However, your spa is not only a source of luxury, but also a breeding ground for bacteria. Maintaining the proper pH and alkalinity levels is crucial for ensuring the cleanliness and safety of your hot tub water.
Understanding Alkalinity, pH, and Their Interconnection
Alkalinity refers to the water's capacity to neutralize acids and bases, acting as a buffer to maintain pH stability. pH, on the other hand, measures the acidity or basicity of the water. These two parameters are closely linked, with pH levels often fluctuating in response to changes in alkalinity.
Why Alkalinity Matters in Hot Tubs
Maintaining correct pH and alkalinity levels is critical for maintaining clean and safe hot tub water. Imbalances in pH can cause a variety of issues affecting water quality and bather comfort.
The Consequences of Imbalance
When pH levels exceed 7.8, the water becomes excessively basic, reducing the effectiveness of chlorine in eliminating pathogens. Conversely, a low pH level (below 7.2) indicates that the water is excessively acidic, which can harm both equipment and bathers.
Recommended Alkalinity Levels
As a hot tub or spa owner, you should aim for alkalinity levels between 80 and 120 ppm to maintain a stable pH and prevent these problems.
Read also: Comprehensive Alkalinity Guide
The Link Between Low Alkalinity and pH Imbalance
Low alkalinity in your spa can lead to a pH imbalance, making it difficult to maintain stable pH levels and increasing chemical demand.
Signs of Low Alkalinity
Signs of low pH and alkalinity include foamy water, which suggests an acidic environment.
Causes of Low Alkalinity in Spas
Several factors can contribute to low alkalinity in hot tubs, including:
Use of Acidic Chemicals
Acidic cleansers or shock treatments can significantly lower alkalinity levels. Overusing chemicals can disrupt the water balance. Regularly adjusting the pH with acidic substances can gradually decrease alkalinity over time.
Soft Water Addition
Soft water, lacking essential minerals for maintaining alkalinity, can decrease TA levels.
Heavy Rainfall
Heavy rainfall can dilute the chemicals in your tub, lowering both alkalinity and pH levels.
Frequent Use and Splashing Out
Regular use of the hot tub leads to water splashing out, which needs to be replenished. Each refill dilutes the concentrations, including TA levels.
Evaporation and Refilling
As water evaporates, chemical concentrations may alter. Adding water to the tub can reduce alkalinity levels.
Organic Contaminants
Organic contaminants like body oils and lotions from bathers can lower Total Alkalinity (TA) levels.
Step-by-Step Guide to Correcting Low Alkalinity
To restore balance to your spa water, follow these steps:
- Test the Water: Use regular testing to track the pH and alkalinity levels.
- Adjust Alkalinity: Address alkalinity before adjusting the pH levels. Use an alkalinity increaser from a professional spa retailer to increase the alkalinity. Baking soda (sodium bicarbonate) can also be used. A general guideline is to add 2 pounds of baking soda per 10,000 gallons of water.
- Adjust pH: After addressing the alkalinity, make the necessary adjustments to fix pH levels. To lower pH and reduce alkalinity, use a pH reducer (often called pH minus). Muriatic acid can also be used in small quantities.
- Re-Test and Repeat: Once all adjustments are complete, re-test the water.
- Monitor Levels: Regularly monitoring pH and alkalinity levels will help your spa remain in balance.
Detailed Steps for Adjustment
To raise alkalinity, deactivate the spa jets and introduce a spa alkalinity increaser. Prioritizing alkalinity first helps facilitate acid neutralization, elevating pH levels to a balanced state. After 24 hours, reevaluate the pH, which may naturally readjust without additional interventions.
To lower alkalinity, deactivate the jets and use a pH reducer. Circulate the product using the jets and re-test the water after two hours, allowing the alkalinity to act as a buffer. One tablespoon of pH reducer will lower alkalinity by about 10 ppm in 250 gallons of water.
Maintaining Stability
When balancing water, focus on alkalinity first. Think of pH as a boat and alkalinity as the anchor. After adjusting alkalinity, wait 24 hours before reassessing the pH.
Addressing High pH and Low Alkalinity
When pH levels rise above 7.8, the water becomes excessively basic, causing ineffective sanitizer performance. To address this, deactivate the spa jets and introduce a spa alkalinity increaser. Once the alkalinity stabilizes, wait 24 hours before reassessing the pH.
Managing Simultaneous Fluctuations
Due to the closely linked relationship between pH and alkalinity, they commonly experience simultaneous fluctuations. Elevated pH and alkalinity levels create cloudy or murky water conditions and increase the risk of bacteria formation.
Additional Tips for Maintaining Balance
- Encourage showering before hot tub use to minimize the introduction of organic contaminants.
- Clean the filter once a month with filter cleaner.
- Shock the water to break down foreign particles.
The Role of Sanitizers and Chlorine
Maintain the correct chlorine levels. Note that chlorine levels may drop significantly if you haven't super-chlorinated recently. Super-chlorinating helps to super-oxidize organic matter in your pool, including algae, oils, ammonia, bugs, and bacteria.
Dealing with Cloudy Water
Cloudy water can be caused by high usage, an inadequate amount of sanitizer, or both. The ideal alkalinity level for a spa is between 80-120ppm. When the total alkalinity is too high, it can cause carbonates to fall out of solution, resulting in cloudy water. When the alkalinity is too low, it causes the pH to fluctuate.
Other Potential Causes
The other possibility is that the calcium hardness is off, often due to the source water containing a high calcium hardness level. To lower your calcium level, simply add a calcium hardness decreaser.
Alternative Solutions
If you have checked all of the above problems and cannot seem to fix the issue, consider using a clarifier.
Understanding Alkalinity and pH: A Deeper Dive
Total alkalinity isn't a relative measure, but a measure of all alkaline chemicals dissolved in a water sample. Total alkalinity typically signifies the concentration of hydroxides, carbonates, bicarbonates, and other alkaloids within your sample.
The Importance of Alkaloids
A higher concentration of alkaloids makes your hot tub's pH more stable, requiring more of a given substance to change its concentration of alkaloids.
Consequences of Low Alkalinity
Low total alkalinity is detrimental to your hot tub's components, potentially causing the surface of the shell to become etched or pitted. Metal parts in contact with water that has low total alkalinity can corrode, endangering heating elements, pipes, and heaters.
Consequences of High Alkalinity
On the other hand, 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 ineffective and cause green water and bacteria to grow.
Natural Ways to Test and Raise Alkalinity
Check and retest the pH level of water 3-4 hours after making adjustments.
Balancing Act: Maintaining pH and Alkalinity Together
Maintaining a balance between pH and alkalinity is crucial for maintaining stable water chemistry. When making adjustments, it’s important to monitor both levels to ensure they are in sync.
Seeking Professional Guidance
If you’re not sure how to manage pH and alkalinity, it’s best to ask a professional for personalized guidance.
Dichlor and Bleach: A Detailed Explanation
Dichlor has little effect on pH & TA except that it adds CYA (Cyanuric acid). CYA has a stabilizing effect on the sanitizer which helps protect from sanitizer depletion due to sunlight exposure. Dichlor is used as the sanitizer & tracked until the desired level of CYA is reached, usually 20-40ppm.
Switching from Dichlor to Bleach
Switch from dichlor to bleach after you have gone through enough dichlor to leave behind the desired amount of CYA. The chlorine part of the dichlor "burns off" as it oxidizes contaminants (same as bleach) but the cyanuric acid (CYA) component is left behind & accumulates as you add dichlor.
Using the Pool Calculator
Use the Pool Calculator to do the calculations (www.poolcalculator.com).
The Impact of CYA
The active chlorine level is roughly proportional to the FC/CYA ratio, so as the CYA climbs, the active chlorine level drops unless you raise the FC level proportionately. With the CYA building up over time using Dichlor, the same FC means the active chlorine level is lower and that means it more slowly oxidizes your bather waste.
Borates for pH Stability
Consider using 50 ppm Borates (say, from boric acid) to have your pH be stable, especially if you use aeration jets while soaking. Add that when the TA is at around 50 ppm.