Hot tub water balance cheat sheet
Most hot tub water problems — cloudiness, itchy skin, that "off" smell — trace back to one of five numbers being out of range. Here's the full target chart, and (just as important) the order you should adjust them in so you're not chasing your own tail.
Target levels
| Parameter | Target | Ideal |
|---|---|---|
| Free chlorine (chlorine tubs) | 1.0–3.0 ppm | — |
| Bromine (bromine tubs) | 2.0–4.0 ppm | — |
| pH | 7.2–7.8 | 7.4–7.6 |
| Total alkalinity | 80–120 ppm | — |
| Calcium hardness | 150–250 ppm | — |
Run either chlorine or bromine as your sanitizer — not both. If you use dichlor chlorine, cyanuric acid (CYA) also slowly builds up and quietly weakens your chlorine; once it climbs past ~50 ppm, the usual fix is a partial drain and refill.
Adjust in this order
The parameters affect each other, so sequence matters. Working top-down avoids re-doing steps:
- Total alkalinity first. Alkalinity buffers pH — if it's off, pH won't hold still. Get TA into 80–120 ppm before anything else.
- pH second. With alkalinity stable, nudge pH into 7.4–7.6. This is the range where sanitizer works well and the water is comfortable on skin and equipment.
- Calcium hardness third. Too low corrodes; too high scales. Aim for 150–250 ppm — it drifts slowly, so it needs less frequent attention.
- Sanitizer last. Once the water is balanced, set free chlorine (1–3 ppm) or bromine (2–4 ppm).
A pH of 15 or a sanitizer of 50 means a misread strip or expired reagent, not your water. Acting on a bad reading is how people overshoot. And if sanitizer is already high, don't add more — wait for it to fall back into range.
Soak turns these numbers into exact doses
Enter your test readings and your tub volume, pick your products (liquid chlorine, cal-hypo, dichlor, bromine; soda ash or dry acid), and Soak gives you the precise amount to add — in the right order — with plain-English "re-test" and "don't add more" warnings. Pay once, no subscription, no ads, fully offline.
Sources
- TroubleFreePool — chemistry calculators and wiki (the TFPC methodology behind these ranges)
- AquaChek — test-strip reference ranges
- Industry hot-tub / spa chemistry guidance
General guidance — always confirm with your own test kit and your tub manufacturer's instructions, and adjust gradually.