Quick Answer: The best hot tub test strip for most people is the AquaChek Select 7-in-1, which reads free chlorine, total chlorine, bromine, pH, total alkalinity, hardness, and stabiliser in one 15-second dip and includes a reusable comparator plus an app that scans the strip for you. Bromine users are better served by a bromine-specific 4-in-1 strip, and the Poolmaster 5-way is the cheapest reliable option for chlorine tubs. Strips run about 85% accurate against roughly 98% for a liquid drop kit — so keep a Taylor K-2006 on the shelf for troubleshooting. Whichever you buy, check the expiration date: AquaChek does not guarantee accuracy past the date printed on the bottle.
Test strips are the cheapest item in spa ownership and the one that decides whether every other chemical you buy is dosed correctly or wasted. They are also the item most people quietly get wrong — not by buying the wrong brand, but by using a two-year-old bottle that has been sitting in a humid shed since the tub arrived.
This is the testing-specific companion to our hot tub chemicals guide, where test strips are one of five essentials. That guide answers what to add. This one answers how you know — which strip fits your sanitiser, how accurate strips actually are, and when to stop trusting them and reach for a drop kit.
Hot tub water testing by the numbers
- 85% vs 98% vs 95% — published water-testing comparisons put test strips at roughly 85% accuracy, liquid drop kits using titration at about 98%, and digital testers at about 95%. Strips are accurate enough for routine checks and not accurate enough for diagnosis.
- 24 months is the minimum shelf life AquaChek states for most of its products from the date of manufacture, with an expiration date printed on every bottle — and the company explicitly does not guarantee accuracy beyond it. Heat and humidity shorten that window.
- 0.2 ppm is the free-chlorine precision of the Taylor K-2006 using the FAS-DPD titration method, with reagent bottles good for roughly 100–200 tests — the reason it remains the reference kit for spa troubleshooting.
- 3 ppm free chlorine, 4 ppm bromine, pH 7.2–7.8 are the CDC’s stated minimums for hot-tub water to reliably kill the germs that cause hot-tub rash and respiratory illness. Those three numbers are what your strip exists to confirm.
- 2–3 times a week is the testing cadence for a spa, versus roughly weekly for a pool. Hot water burns off sanitiser far faster, which is why spa strips carry a bromine pad that pool strips often skip.
Our top test-strip picks at a glance
| Product | Type | Reads | Best for | Typical price |
|---|---|---|---|---|
| AquaChek Select 7-in-1 | Strip | FC, TC, bromine, pH, TA, hardness, stabiliser | Best overall | ~$15–$25 / 50 |
| AquaChek bromine 4-in-1 | Strip | Bromine, pH, TA, hardness | Bromine tubs | ~$12–$18 / 50 |
| Poolmaster 5-way | Strip | Chlorine, bromine, pH, TA, hardness | Best budget | ~$8–$14 / 50 |
| AquaChek Silver 7-way (100 ct) | Strip | Same as Select, no comparator | Best bulk value | ~$18–$28 / 100 |
| Taylor K-2006 (FAS-DPD) | Liquid kit | FC to 0.2 ppm, CC, pH, TA, hardness, CYA | Troubleshooting | ~$80–$110 |
Prices checked July 2026 across Amazon and spa-supply listings. Strip pricing is dominated by count, not brand — a 100-count bottle is usually well under twice the price of a 50-count.
1. AquaChek Select 7-in-1 — Best Overall
AquaChek Select Connect 7-in-1 Spa Test Strips
- Reads free chlorine, total chlorine, total bromine, pH, total alkalinity, total hardness, and stabiliser from one dip.
- Ships with a reusable colour comparator, so you are not squinting at a curved bottle label.
- The free AquaChek app scans the strip with your phone camera and returns dosing advice.
- AquaChek is the most widely stocked strip brand in the trade, with over 35 years in water testing.
Because strips expire whether you use them or not, this is a category where a standing reorder beats a bulk hoard — if you are already rebuying filters and sanitiser on a cycle, you can try Prime free for 30 days and have the small, frequent orders ship free rather than padding each cart to hit a shipping threshold.
The Select earns the top spot on two features rather than on chemistry: the separate comparator card and the app. Colour-matching a wet strip against a printed cylinder is the weakest link in strip testing, and a flat comparator you can lay the strip directly beside removes most of the guesswork. The stabiliser (cyanuric acid) pad matters less in a spa than a pool — you are not fighting sunlight under a cover — but it is genuinely useful if you dose with dichlor, which adds CYA every single time you shock.
2. AquaChek Bromine 4-in-1 — Best for Bromine Tubs
AquaChek Bromine Spa Test Strips (4-in-1)
- Prints the bromine scale directly instead of asking you to convert a chlorine reading.
- Includes a total hardness pad, because scale forms faster at spa temperatures.
- Targets the CDC's 4 ppm bromine minimum without mental arithmetic mid-test.
- The right strip if you run bromine tablets in a floating dispenser.
Bromine is the more forgiving sanitiser at hot-tub temperatures, which is why so many inflatable owners end up on it — see our hot tub chemicals guide for the chlorine-versus-bromine decision itself. The catch is that many general pool strips have no true bromine pad; they read total chlorine and expect you to multiply by roughly 2.25 to get bromine. That conversion is where dosing errors creep in. A dedicated bromine strip prints the number you actually need. AquaChek also notes that its bromine strips include hardness specifically because warm water accelerates scale build-up — a spa-specific concern that pool strips often ignore.
3. Poolmaster 5-Way — Best Budget
Poolmaster 5-Way Pool & Spa Test Strips
- Covers chlorine, bromine, pH, total alkalinity, and hardness — everything a spa routinely needs.
- Colour blocks are larger and more separated than most rivals, which helps in poor light.
- Typically the cheapest per-test option that is still genuinely readable.
- Works for both chlorine and bromine users, so one bottle covers a switch.
Skip the stabiliser pad and the price drops noticeably. For an inflatable or plug-and-play spa that gets drained every month or two anyway, cyanuric acid rarely has time to accumulate into a problem, so a five-way strip covers the real decisions. The Poolmaster’s advantage over other cheap strips is legibility: the colour blocks are physically bigger, which matters more than it sounds when you are matching a damp alkalinity pad at dusk.
4. AquaChek Silver 7-Way (100 Count) — Best Bulk Value
AquaChek Silver 7-Way Test Strips, 100 Count
- Same seven readings as the Select, in a 100-strip bottle at a lower per-test cost.
- No comparator card — you match against the bottle label instead.
- Sensible only if you will genuinely use 100 strips before the printed expiration date.
- At 2–3 tests a week, a 100-count bottle is roughly eight months of testing.
Do the arithmetic before you buy the big bottle. At the spa cadence of two to three tests a week, 100 strips is around eight months — comfortably inside a 24-month shelf life, so the bulk bottle is the right call for a year-round tub. If you drain and store the tub for the winter, it is not: a bottle that sits half-used through a cold, damp off-season is exactly the scenario AquaChek warns shortens shelf life. Buy 50 at a time and keep them indoors instead.
5. Taylor K-2006 — Best for Troubleshooting
Taylor K-2006 Complete Test Kit (FAS-DPD)
- FAS-DPD titration reads free chlorine to 0.2 ppm — an order of magnitude finer than a strip's colour block.
- Separates free from combined chlorine, which is what actually diagnoses the "chlorine smell" problem.
- Also covers pH, total alkalinity, calcium hardness, and cyanuric acid.
- Reagents are consumable and have their own shelf life — replace them, not the whole kit.
This is not a replacement for strips and should not be treated as one — nobody runs a titration before a Tuesday soak. It is the tool you own for the week the water goes cloudy, the strips read fine but the tub smells of chlorine, or you are chasing a pH that will not hold. The distinction that solves most of those cases is free versus combined chlorine, which a strip’s single “total chlorine” pad physically cannot give you. A strong chlorine smell almost always means combined chlorine is high and you need to shock harder, not that you have too much sanitiser — and the K-2006 is what proves it.
How to get an accurate reading in 30 seconds
- Check the expiration date before the water. If the bottle is out of date or the strips look mottled, throw it out. Every other step here is wasted on a degraded strip.
- Dip elbow-deep, away from the jets. Surface water and freshly dosed water near a return line are not representative. Reach down about 18 inches at the far side of the tub.
- Dip and pull straight out — do not shake. Shaking bleeds one pad’s reagent into the next, which is the classic cause of an impossible alkalinity reading.
- Read at the time printed on the label, in daylight. Most pads have a 15-second window and keep developing afterwards. Coloured tub lighting will skew every match you make.
- Cap the bottle immediately and store it indoors. Humidity is the enemy; a tightly capped bottle kept out of heat lasts to its printed date, one left open by the tub does not.
What testing actually costs per year
A 100-count bottle of seven-way strips at two to three tests a week runs roughly $25–$40 a year — the cheapest line item in spa ownership by a wide margin, and the one that protects the $15–$40 a month you spend on hot tub chemicals. Add a Taylor kit once at around $80–$110 and replace only the reagents as they run down.
The false economy is stretching a bottle past its date to save $15. An expired strip that reads 3 ppm when the water is actually at 1 ppm does not save you money — it costs you a drain-and-refill, and the maintenance schedule exists precisely so you never get there. Testing is also only half the loop: chemistry cannot fix water that is not being filtered properly, so check that you are running the right cartridge in our best hot tub filters guide. Because strips, filters, and sanitiser are all recurring buys, it is worth checking whether Amazon Prime is worth it for hot tub shoppers before you set up the reorder cycle.
The bottom line
The AquaChek Select 7-in-1 is the best hot tub test strip for most owners: seven readings, a reusable comparator, and an app that removes the colour-matching guesswork. Bromine users should buy a bromine-specific 4-in-1 so they are reading the real number rather than converting a chlorine pad, and the Poolmaster 5-way is the honest budget pick. Keep a Taylor K-2006 for the weeks nothing adds up. And treat the expiration date as the actual spec — a fresh cheap strip beats an expired premium one every time.
New to spa chemistry generally? Start with the hot tub chemicals guide for what to buy, the hot tub maintenance guide for when to do it, and the best hot tub accessories roundup for the rest of the kit. Still choosing a tub? See our best inflatable hot tub roundup, the best Intex PureSpa models, or the Coleman SaluSpa lineup.