Hot tub and swim spa chemical balance means keeping your water “just right” so it’s ready to enjoy, feels comfortable on your skin and helps protect surfaces and equipment.
When it’s out of balance, water can cause problems, including permanent damage to hot tub or swim spa walls, deck and equipment.
The Top 3 Key Factors of Water Chemistry
Keeping these within the ideal hot tub or swim spa water chemistry levels ensures proper water balance.
- Total Alkalinity
- pH Levels
- Calcium Hardness
Total Alkalinity (TA)
Total Alkalinity refers to how well your water can resist changes in pH. Think of it as a buffer that keeps your pH level stable. Keeping TA in the ideal range helps everything else stay balanced.
pH
Your sanitizer’s effectiveness depends heavily on hot tub chemistry. Maintaining proper pH balance helps chlorine or bromine work efficiently.
Calcium Hardness or Total Hardness
Calcium Hardness or Total Hardness measures the amount of dissolved calcium (and some magnesium) in your water. It plays a key role in overall water balance, along with pH and Total Alkalinity. Low Calcium Hardness = soft, corrosive water. High Calcium Hardness = hard, scale-forming water.
Recommended Guidelines for Optimal Hot Tub or Swim Spa Chemistry
| Water Chemistry | Min. | Ideal | Max. | Testing Frequency |
|---|---|---|---|---|
| Free Chlorine with Minerals (ppm) | 1.0 | 1.0–2.0 | 1.0 | weekly |
| Free Chlorine without Minerals (ppm) | 1.0 | 2.0–4.0 | 5.0 | at least twice a week |
| pH | 7.2 | 7.4–7.6 | 7.8 | at least twice a week |
| Total Alkalinity (ppm) | 80 | 80–120 | 120 | weekly |
| Total Hardness (ppm) | 150 | 150–250 | 250 | weekly |
Free Chlorine with Minerals refers to the amount of chlorine that should be present when using FROG®
How to Balance Hot Tub or Swim Spa Water (Step-by-Step)
Follow this simple process for balancing spa water:
Step 1: Test the Water
Check Total Alkalinity, pH and Calcium Hardness levels in order. Use test strips or a water test kit to check your water chemistry and make sure it’s properly balanced.
Step 2: Adjust Total Alkalinity First
- Ideal Range: 80 – 120 ppm
- If low: Add TA Increaser or TA Up
- If high: Add pH Decreaser or pH Down (this chemical is used to lower both TA and pH)
- Make sure TA is in the ideal range before moving on to balance pH
Step 3: Adjust pH Next
- Ideal Range: 7.2 – 7.6
- If low: Add pH Increaser or pH Up
- If high: Add pH Decreaser or pH Down
- Wait 6 hours, test and tweak if needed
Step 4: Adjust Calcium Hardness Next
- Ideal Range: 150 – 250 ppm
- If low: Add Hardness Increaser
- Wait 6 hours, test and adjust if needed
- Do not overdose – there is not Hardness Decreaser!
Step 5: Sanitize
Use chlorine or bromine to maintain clean water.
Step 6: Circulate and Re-test
Run the jets for 15-30 minutes after adding chemicals. Retest and fine-tune if needed.
What Causes Water Imbalance?
Understanding what causes hot tub or swim spa water imbalance helps prevent common water chemistry issues. The biggest factors include:
- Heavy use
- Body oils, lotions and debris
- Water temperature changes
- Adding fresh water
- Chemical adjustments
Understanding TDS (Total Dissolved Solids)
TDS is a hidden contributor to hot tub or swim spa water problems. TDS is the total of all dissolved solid matter in the water, including:
- Minerals
- Chemical residue
- Oils and contaminants
TDS builds up as water evaporates and the minerals, particles and chemical residues are left behind. Signs of high TDS include:
- Difficulty maintaining water balance
- Cloudy water
- Scale buildup or corrosion
- Harsh water
You don’t need to check TDS levels as often as you check Total Alkalinity, pH and Calcium Hardness, but you will need to check them routinely. Monthly is good practice. The only way to remedy high TDS levels is to partially drain the hot tub or swim spa and top it off with fresh water.
Pro Tips for Maintaining Balanced Water
- Test water 2–3 times per week
- Use quality chemicals consistently
- Shock weekly or after heavy use
- Clean filters regularly
- Monitor changes after adding new water
See, Feel and Smell the Difference
FROG® Sanitizing Systems transform your hot tub or swim spa by combining proprietary FROG Sanitizing Minerals® with low levels of chlorine to destroy bacteria. The result is Fresh Mineral Water®∞, our signature water quality experience that’s gentler on skin and free from the harsh, over-chlorinated feel of traditional hot tub care.
- Uses up to 75% less chlorine*
- Creates water that is Cleaner, Clearer and Softer
- Easier on skin, swimsuits and spa surfaces
- No harsh odors
* Compared to the minimum ANSI recommended chlorine level of 2.0 ppm for a hot tub or swim spa
∞ Cleaner, Clearer and Softer water for pools, hot tubs and swim spas
