Maintaining the right alkalinity levels in your hot tub is crucial for clean, clear, and comfortable water. If alkalinity is too high, it can cause skin irritation, cloudy water, calcium buildup, and reduce the effectiveness of sanitizers like chlorine. This guide by The Trade Table will explain how to lower alkalinity in a hot tub, why it matters, and how to keep it balanced for the long run.
Alkalinity is measured in parts per million (ppm) and helps keep your water’s pH levels stable. If alkalinity is too high, pH levels can spike, leading to a range of problems:
✅ Limescale & Calcium Deposits – Hard water buildup clogs jets and makes water cloudy.
✅ Reduced Sanitizer Effectiveness – Chlorine and bromine work less effectively, making water unsafe.
✅ Skin & Eye Irritation – High alkalinity can cause itching, redness, and dryness.
✅ Increased Maintenance Costs – More chemicals are needed to balance your water, increasing upkeep expenses.
💡 Ideal Alkalinity Range: 80–120 ppm
💡 Ideal pH Range: 7.2–7.8
If your hot tub’s pH is consistently above 8.0, your alkalinity is too high and needs to be corrected.
Several factors can cause alkalinity to rise over time, including:
🚿 Body Products & Oils – Sweat, sunscreen, lotion, and perfumes add unwanted chemicals.
🧪 Overuse of Chemicals – Too much pH-increasing agents (like baking soda) can spike alkalinity.
💦 Hard Water Source – Some tap water has naturally high alkalinity levels.
🌡️ Evaporation & Refill Cycles – Water loss increases the concentration of dissolved minerals.
To prevent high alkalinity, always shower before entering and regularly test your water.
You’ll need to test your water before making any adjustments. There are two main ways to do this:
1️⃣ Test Strips – Inexpensive and easy to use, but not always highly precise.
2️⃣ Digital Testers – More accurate but cost more upfront.
Dip the strip into the water, wait a few seconds, and compare the color to the chart provided. If the reading shows alkalinity above 120 ppm, it’s time to lower it.
Once you've determined that alkalinity is too high, follow these steps to bring it back to normal levels.
To lower alkalinity, you’ll need to use an acid-based product:
✔ Sodium Bisulfate (Dry Acid) – A common spa pH reducer (safer & easier to handle).
✔ Muriatic Acid (Liquid Acid) – Stronger and faster-acting but requires caution when handling.
✔ White Vinegar (Emergency Option) – Less effective but works in a pinch.
Before adding any chemicals, turn on your hot tub’s jets. This helps distribute the pH reducer evenly.
Leave your hot tub running overnight and allow the water to mix fully.
After 24 hours, test your alkalinity levels again. If it’s still too high, repeat the process in small increments.
After fixing high alkalinity, follow these maintenance tips to keep it from rising again:
✅ Test your hot tub water daily using pH strips or a digital tester.
✅ Always adjust alkalinity before pH – it stabilizes pH levels.
✅ Shower before entering to reduce sweat, oils, and lotions.
✅ Drain & refill the tub every 3–4 months to remove built-up chemicals.
✅ Keep pH balancers on hand so you can fix small imbalances before they become bigger issues.
💬 Will alkalinity decrease on its own?
➡ Yes, but very slowly. High alkalinity can cause scaling and bacteria buildup before it naturally decreases. It’s better to adjust it quickly.
💬 What neutralizes alkalinity in a hot tub?
➡ Acids like sodium bisulfate or muriatic acid effectively lower alkalinity.
💬 Does shocking a hot tub lower alkalinity?
➡ No! Chlorine shock raises pH and alkalinity. Use non-chlorine shock if you need to sanitize the water without increasing pH.
💬 Does raising alkalinity raise pH in a hot tub?
➡ Not always. Alkalinity buffers pH, meaning it keeps pH from fluctuating too much. But adding too much alkalinity increaser can also raise pH levels.
Balancing alkalinity in your hot tub is essential for clean, comfortable, and well-maintained water. By testing regularly, adjusting when necessary, and following good maintenance habits, you can avoid skin irritation, cloudy water, and costly repairs.
If you're looking for quality hot tubs check out The Trade Table for everything you need!
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