How to Use Hot Tub Test Strips (and Read the Results)
Every good hot tub routine starts with a test. Strips are the quickest way to see where your sanitizer and water balance stand, so you add only what the water needs instead of guessing.
How often to test
Test two or three times a week, plus before you shock, after heavy use and after a refill. Testing often makes each adjustment small and easy.
Pick the right strips
- Chlorine tubs: Leisure Time 4-way strips check free chlorine, pH, total alkalinity and calcium hardness. They're made for chlorine and ozone systems.
- Bromine tubs, or if you want more readings: JNW 7-way strips include a bromine pad along with chlorine, pH, alkalinity and hardness.
Browse all hot tub test strips.
How to use test strips, step by step
- Use dry hands and take one strip out, then close the bottle right away. Moisture in the bottle ruins the rest of the strips.
- Dip the strip about elbow deep, away from the jets and any spot where you just added chemicals, for the time on the label (often about 2 seconds).
- Shake off the extra water once and hold the strip level with the pads facing up.
- Read it on time. Some strips are read right away and some after a short wait, so check the bottle. Compare each pad to the color chart in good light.
What the readings mean
These are common ranges for home hot tubs. If your spa maker lists different numbers, go with theirs.
- Free chlorine: about 3 to 5 ppm (or bromine about 4 to 6 ppm). Low? Add sanitizer. Very high? Leave the cover off and skip doses until it drops.
- pH: about 7.2 to 7.8. Low? Add Spa Up. High? Add Spa Down.
- Total alkalinity: about 80 to 120 ppm. Fix this before pH. See how to balance pH and alkalinity.
- Calcium hardness: about 150 to 250 ppm. Low hardness can lead to foam; high hardness can lead to scale. Shop water balance.
Tips for accurate results
- Store strips in a cool, dry place, not in the hot tub cabinet or a steamy bathroom.
- Check the expiration date. Old strips can give false readings.
- Adjust one thing at a time, let the jets run, then re-test before adding more.
- If a reading looks wrong, test again with a fresh strip before you add anything.
Want the full weekly plan? See our hot tub chemical guide.
Related reading:
Safety first: always follow the directions on the product label and your hot tub maker's manual. Add chemicals to the water one at a time, never mix chemicals together, and store them dry, cool and out of reach of kids and pets. Questions? Send us a message.
