Accurate water testing is the foundation of hot tub maintenance. Bad test strips lead to bad chemical decisions, which lead to cloudy water, skin irritation, and damaged equipment.
Here are the strips we would look at first for a hot tub, and what each one is suited to. No home test strip is lab-accurate, so the section on accuracy below matters more than any single brand.
Quick Picks
AquaDoc 7-in-1 Test Strips TOP PICK
A 7-in-1 strip that covers both chlorine and bromine tubs, with color pads that are easy to tell apart.
- Tests: Free Chlorine, Bromine, pH, Alkalinity, Hardness, Cyanuric Acid, Total Chlorine
- Clear color differentiation
LaMotte Insta-Test 4 Plus TESTING BRAND
From LaMotte, a long-established maker of water-testing equipment. A 5-in-1 strip for owners who want a testing-specialist brand.
- Tests: Free Chlorine, Bromine, Alkalinity, pH, Hardness
Pawfly 7-in-1 Test Strips BUDGET PICK
A large 150-strip bottle for people who test often.
- Tests: Chlorine, Bromine, pH, Alkalinity, Hardness, Cyanuric Acid, Total Chlorine
- 150 strips per bottle
- Good for weekly testing
Best for Bromine Systems
If your tub uses bromine, you need a strip with a bromine pad — a chlorine pad cannot read bromine. These two are made for bromine and FROG tubs.
AquaChek Bromine 4-in-1 Test Strips BEST BROMINE
Made for bromine spas, with a bromine pad and a bromine scale on the chart.
- Tests: Bromine, pH, Alkalinity, Hardness
- Calibrated for bromine (not repurposed chlorine strips)
- Clear color pads with distinct steps
FROG @ease Test Strips FOR FROG SYSTEMS
If you run a FROG @ease sanitizing system, use the FROG-branded test strips. They're specifically designed to read the SmartChlor residual that FROG uses — standard chlorine strips will give misleading low readings with FROG systems.
- Tests: SmartChlor, pH, Alkalinity
- Required for accurate readings on FROG @ease systems
What to Look for in Test Strips
1. Number of Tests (5-way vs 7-way)
For hot tubs, you need at minimum:
- Sanitizer (chlorine or bromine) - kills bacteria
- pH - comfort and sanitizer effectiveness
- Alkalinity - pH stability
- Hardness - prevents equipment damage
7-way strips add Cyanuric Acid (CYA) which matters more for outdoor pools than hot tubs.
2. Color Clarity
The biggest complaint about test strips is hard-to-read colors. Some brands have colors that look nearly identical, making it impossible to tell if your pH is 7.2 or 7.8.
Not sure what the colors are telling you? See our hot tub test strip color chart for the ideal ranges.
3. Accuracy vs Liquid Tests
Test strips will never be as accurate as liquid reagent tests. For routine checks a fresh, well-stored strip read on time is fine; when you need an exact number, use a liquid kit.
What Makes a Hot Tub Test Strip Accurate?
No test strip is lab-accurate — every strip is matching a color by eye. What decides accuracy is whether the strip is fresh, stored right, read on time and read on the right scale. In practice, these matter more than the brand:
- In date and sealed. Strips lose accuracy once they pass the date on the bottle or soak up moisture. Close the cap right after taking one out, and keep the bottle somewhere cool and dry — not on the hot tub cover.
- The right pad for your sanitizer. A bromine tub needs a strip with a bromine pad, and a FROG @ease tub needs the FROG strips. A chlorine pad on a bromine tub reads wrong no matter how good the strip is.
- Exact timing. Read when the bottle says, not a minute later — colors keep changing.
- Daylight, not a porch light. Warm or dim light shifts every color on the chart.
- Clear steps between colors. Strips whose chart swatches look nearly the same are hard to read accurately, whatever they promise.
Bromine reads on its own scale (its numbers run higher than chlorine’s), so always compare a bromine pad against the bromine side of the chart. When you need an exact number — a reading that looks wrong, water that will not balance, or after a drain and refill — a liquid drop-count test kit or a pool store test is the more precise check. For how to read each pad, see how to read hot tub and pool test strips.
Comparison Table
| Brand | Tests | Count | Best For |
|---|---|---|---|
| AquaDoc 7-in-1 | 7 | 50 | Best overall |
| LaMotte Insta-Test | 5 | 50 | Testing-specialist brand |
| Pawfly 7-in-1 | 6 | 150 | Budget / high-frequency |
| AquaChek Bromine | 4 | 50 | Bromine systems |
| FROG @ease Strips | 3 | 30 | FROG @ease systems only |
How Often Should You Test?
- Minimum: 2-3 times per week
- After heavy use: Same day
- After adding chemicals: Wait as long as the product label says, then test
- After refilling: Daily for the first week
Tired of Guessing at Test Strip Colors?
HTReminder reads your test strips with AI and suggests what to adjust; your product labels decide the amounts.
Get HTReminder FreeCommon Test Strip Mistakes
- Reading too late - Read strips within the time printed on the bottle. Colors keep changing.
- Wet fingers - Water on your hands dilutes the reagents. Keep strips dry until use.
- Old strips - Test strips expire. Check the date and store in a cool, dry place.
- Wrong angle - Hold the strip horizontal. Tilting causes colors to run together.
Final Recommendation
For most hot tub owners, the AquaDoc 7-in-1 strips are an easy place to start: one strip covers chlorine or bromine, and the pads are easy to tell apart. The HTReminder app can read the strip for you and suggest what to try — always follow the manufacturer’s directions for amounts.
If you test frequently and want to save money, the Pawfly 7-in-1 150-count strips are a solid budget choice.
If you prefer a testing-specialist brand, look at LaMotte Insta-Test.