When it comes to maintaining the perfect water chemistry in your hot tub, understanding the difference between soda ash and baking soda is essential. Both are popular options for adjusting pH and alkalinity levels, but using the wrong one can throw your water balance off track. In this article, we’ll break down the key differences between soda ash and baking soda, and help you decide which is better for your hot tub — especially if you’re using the Sutro Smart Water Monitor to track your levels in real-time.
What Is Soda Ash?
Soda ash, also known as sodium carbonate (Na₂CO₃), is commonly used to raise pH levels in pools and hot tubs. It has a high pH of around 11.4, making it effective at increasing the pH of your water without significantly affecting total alkalinity.
When to use soda ash:
- Your pH is too low (below 7.2)
- You want to raise pH without raising alkalinity too much
What Is Baking Soda?
Baking soda, or sodium bicarbonate (NaHCO₃), is primarily used to raise total alkalinity in hot tub water. It has a pH of around 8.3, so while it can raise pH slightly, its main effect is on alkalinity stability.
When to use baking soda:
- Your alkalinity is low (below 80 ppm)
- Your pH is already balanced, but your water feels corrosive or unstable
Soda Ash vs. Baking Soda: Key Differences
| Property | Soda Ash | Baking Soda |
|---|---|---|
| Chemical Name | Sodium Carbonate | Sodium Bicarbonate |
| Primary Use | Raise pH | Raise Alkalinity |
| Effect on pH | Raises pH significantly | Slight increase |
| Effect on Alkalinity | Small increase | Large increase |
| Ideal Use Case | Low pH, normal alkalinity | Low alkalinity, balanced pH |
Which Should You Use in Your Hot Tub?
The answer depends on what your water actually needs. That’s where a smart water monitor like Sutro can make life much easier.
The Sutro Water Monitoring System takes the guesswork out of water chemistry by giving you real-time data on your hot tub's pH, alkalinity, and sanitizer levels — and even tells you exactly what to add and when.
With Sutro:
- If your pH is low but alkalinity is normal → add soda ash.
- If your alkalinity is low but pH is okay → add baking soda.
- If both are low → Sutro helps you balance the right amount of each.
Why Water Balance Matters in a Hot Tub
Maintaining proper water chemistry isn’t just about clear water — it’s about protecting your skin, your hot tub equipment, and your overall comfort.
- Low pH can lead to corrosion of your heater, jets, and other components.
- Low alkalinity causes water to be unstable and more prone to pH swings.
- Balanced water helps your sanitizer work more effectively and keeps your water crystal clear.
Let Sutro Take the Guesswork Out
Using soda ash or baking soda correctly requires knowing the exact status of your water. That’s why thousands of hot tub owners rely on Sutro’s smart water monitoring system to automatically test water 3x/day and provide easy, app-based recommendations.
Ready to stop guessing and start enjoying?
👉 Shop the Sutro Smart Monitor now
Final Thoughts
When it comes to soda ash vs. baking soda, it’s not about which is better — it’s about using the right one for the right job. With accurate testing and a clear understanding of your water’s needs, you can keep your hot tub in perfect balance.
Let Sutro handle the science so you can soak stress-free.