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Hot tub test strips: pool bands, bromine and holiday lets

Updated: 21 October 2026

A swimming-pool chlorine figure of about 1 mg/l is the wrong band for a hot tub, and a spa figure of 3–5 mg/l is the wrong band for the pool. The strip only shows a colour. The programme depends on whether the tub is a private Lay-Z-Spa, a domestic tub you run to BISHTA's sheet, or a holiday let under HSG282. Prices come from the [pool test strips comparison](/hub/pool-care/pool-test-strips) on 19 October 2026. We did not lab-test a pad. The dip itself is on [how to use pool test strips](/hub/pool-care/pool-test-strips/sub/pool-test-strips-how-to-use). A qualifying purchase can earn a commission at no extra cost to you.

A swimming-pool chlorine figure of about 1 mg/l is the wrong band for a hot tub, and a spa figure of 3–5 mg/l is the wrong band for the pool. The strip only shows a colour.

Our top picks

Clearwater Clearwater 4-in-1 test strips, 50

Best overall

Clearwater Clearwater 4-in-1 test strips, 50
7.1/10about £9.99
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HOVIRAN HOVIRAN 3-in-1 pool test strips, 125

Best value

HOVIRAN HOVIRAN 3-in-1 pool test strips, 125
6.9/10about £7.29
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EASYTEST EASYTEST 7-way pool test strips, 150

Rank 3

EASYTEST EASYTEST 7-way pool test strips, 150
9.0/10about £15.99
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On this page
  1. 1.A hot tub is not a public pool
  2. 2.Chlorine, bromine and pH on a domestic tub
  3. 3.How often, and in what order
  4. 4.If you let the tub

A hot tub is not a public pool

PWTAG is the standard HSE points to for a managed swimming pool. For hypochlorite, that code keeps pH at 7.0–7.4, ideally 7.0–7.2, with free chlorine about 1 mg/l at the lower pH and about 2 mg/l at pH 7.2–7.4. A residual above 3 mg/l should not be necessary. That is a pool plant figure. If your strip reads 1 mg/l in a hot tub and you stop there, you are under-dosing the spa against the hot-tub charts below. Lay-Z-Spa's chemicals guide tests before use and aims at total alkalinity 80–120 ppm, pH 7.2–7.6 and chlorine 3–5 ppm, adjusted in that order, with at least two hours between chemical types. BISHTA's domestic sheet uses chlorine 3–5 mg/l, pH 7.0–7.6 and alkalinity 80–120 mg/l, tested before use. HSG282, for a spa pool that is a work activity, sets pH 7.0–7.6 and, at pH 7, free chlorine 3–5 mg/l. Which pads to buy is on the pool test strips buying guide.

Chlorine, bromine and pH on a domestic tub

Bromine is not the same number as chlorine. BISHTA's domestic sheet puts bromine at 2–4 mg/l. HSG282, at pH 7, puts total active bromine at 4–6 mg/l for a business spa. Lay-Z-Spa's Clearwater strip page states bromine 6–10 ppm, which is wider than both. A private Lay-Z-Spa on chlorine uses 3–5 ppm. Bromine at home to BISHTA uses 2–4 mg/l, not the 6–10 ppm line. A let tub uses the HSG282 band. The strip has to name the chemical. Clearwater, EASYTEST, HOVIRAN and the seven-way bottles in this set name bromine. Nacerlary says free chlorine and bromine share one pad, so you read the scale for the sanitiser you use and you do not add the scales. VivaTest and AquaChek yellow do not name bromine. A chlorine-only bottle is the wrong tool on a bromine tub.
Clearwater Clearwater 4-in-1 test strips, 50

Testsieger

Clearwater Clearwater 4-in-1 test strips, 50
7.1/10about £9.99
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How often, and in what order

Test before anyone gets in. BISHTA's domestic sheet says before use. Lay-Z-Spa's guide uses the same habit and a set order: total alkalinity, then pH, then chlorine, with at least two hours between chemical types. That twice-a-week line is a domestic minimum. It is not the rule for a let tub. Write the three numbers down in daylight. The seconds stay on the bottle. A strip from last month is not today's test. Bin an opened bottle that is past the days the label states.

If you let the tub

A holiday let is not a garden accessory. BISHTA's note on HSG282 treats a business spa, including many holiday lets, as a duty to test chlorine or bromine and pH at least twice a day, to change the water at least weekly or between groups, and to have monthly microbiology plus a quarterly legionella test. HSG282 sets pH 7.0–7.6, and at pH 7 a free chlorine of 3–5 mg/l or total active bromine of 4–6 mg/l. Twice a day means a morning reading and a later reading. A colour strip cannot finish that list. It does not replace monthly microbiology or a legionella sample. Nothing in this set is HSG282-approved. Which extra pads are worth opening every day is on 3 in 1 vs 7 in 1 pool test strips. For a let tub, the daily job is sanitiser and pH, twice, written down.

Common questions

What chlorine and pH should a Lay-Z-Spa sit at?
Lay-Z-Spa’s own guide says chlorine 3–5 ppm, pH 7.2–7.6 and total alkalinity 80–120 ppm, with alkalinity adjusted first. BISHTA’s domestic chlorine band is also 3–5 mg/l, with pH 7.0–7.6. A public-pool figure near 1 mg/l is the wrong target. Do not average in a shop page that prints 1–3 ppm for the same brand of tub.
Is bromine the same number as chlorine?
No. BISHTA’s domestic bromine band is 2–4 mg/l. HSG282 uses 4–6 mg/l total active bromine at pH 7 for a business spa. Lay-Z-Spa’s strip page states 6–10 ppm bromine. Use the band that belongs to your programme. Do not add a chlorine reading to a bromine reading on a shared pad.
How often do I test a tub I use at weekends?
Before you get in, including the first use after several quiet days. BISHTA says test before use. A twice-a-week habit is a floor when the tub is idle, not a substitute for a test on the evening you lift the cover. Record alkalinity, pH and sanitiser, in that dosing order, with a gap between chemicals.
Does a holiday let have to test twice a day?
Yes, if the tub is a business spa under HSG282, which BISHTA says includes many holiday lets. Chlorine or bromine and pH at least twice a day, a water change at least weekly or between groups, monthly microbiology and a quarterly legionella test. A private tub in your own garden is not automatically that duty. A strip does not replace the samples.
Does a strip replace a legionella test?
No. A colour match for chlorine, bromine or pH is not microbiology. A let tub under HSG282 still needs the monthly microbiology and the quarterly legionella test BISHTA describes. Staying inside a sanitiser band is part of the routine. It is not the whole duty, and it does not make the water safe by itself.

Related pages

Best hot tub test strips

Pool test strips

3 in 1 vs 7 in 1 pool test strips: which extra pads

Best pool test strips UK: pads, count and expiry date

How to use pool test strips: seconds, light and white pads

Sources

Public UK sources for pool and spa water targets, taken from the research digest. Listing prices, stars and review counts are from amazon.co.uk on 19 October 2026. No bottle here is a PWTAG approval.

  1. HSE — swimming pool safety (retrieved 19 October 2026)
  2. PWTAG code of practice (retrieved 19 October 2026)
  3. PWTAG standards (retrieved 19 October 2026)
  4. HSE — HSG282, control of legionella and other infectious agents in spa-pool systems (retrieved 19 October 2026)
  5. BISHTA — water treatment (retrieved 19 October 2026)
  6. BISHTA — daily, weekly, monthly and annual hot tub checks (retrieved 19 October 2026)
  7. Lovibond UK leisure — water testing (retrieved 19 October 2026)
  8. Amazon.co.uk best sellers — Pool & Hot Tub Testers (retrieved 19 October 2026)