Inflatable hot tub care
An inflatable hot tub holds only about 177–210 gallons, so chemical doses are tiny.
Always follow your product’s label directions. Pool and spa chlorine, bromine, shock and algaecides are EPA-registered pesticides: use products labeled for pool or spa use, and don’t swim or soak until levels are within the limit on your product’s label. If this page and a label disagree, the label wins.
On this page (8 sections)
Raising free chlorine by 3 ppm in a 210-gallon Intex PureSpa takes about 4.3 g of 56% dichlor granules, or 7.8 teaspoons of 6% bleach. Aim for 3–4 ppm, which fits both the CDC's hot tub minimum and Intex's own range.
The calculator starts with a 250-gallon tub at 1 ppm free chlorine (FC) and pH 7.8. Enter your tub's capacity (from the table below or your manual) and your latest test.
Capacities (Intex PureSpa 210 gal, Bestway SaluSpa 177 gal)
Use the capacity your manufacturer publishes, not a guess from the outside size: the thick inflatable walls take up much of the footprint. The two models below are from manufacturer pages we checked. Other tubs vary by model and year, so look for the water capacity on the box or in your manual.
| Model | Capacity | Fill basis | Real ÷ nominal geometry | Source |
|---|---|---|---|---|
| Bestway SaluSpa Hot Springs AirJet 2-4 person | 177 gal670 L | not stated | — | manufacturer |
| Intex PureSpa Bubble Deluxe 4-person (round inflatable) | 210 gal795 L | not stated | — | manufacturer |
Capacities read on manufacturer pages on 2026-09-29. "Real ÷ nominal geometry" below 1 means the box size overstates the water volume.
Small volume is the key fact in inflatable tub care. Two people add a lot of sweat and lotion to 200 gallons, chlorine is used up fast at 100 °F or more, and one extra scoop overshoots. For other tub sizes, see hot tub gallons by size. If you also own an Intex pool, its capacities are on the Intex pool sizes page.
Start-up
- Set the tub up on a flat, cleared surface, and fill it with a garden hose to the fill line.
- Install clean filter cartridges and start the heater with the insulated cover on. Heating from cold tap water can take many hours. Bestway's manual lists heating times from several hours to most of a day, depending on air and water temperature.
- Test the fresh water. Adjust alkalinity first, then pH, then add chlorine.
- Raise free chlorine to 3–4 ppm before the first soak.
| Product | Change | 177 gal | 210 gal |
|---|---|---|---|
| Dichlor granules 56% | +1 ppm FC | 1.2 g | 1.4 g |
| Dichlor granules 56% | +3 ppm FC | 3.6 g | 4.3 g |
| Household bleach 6% | +1 ppm FC | 2.2 tsp (0.37 fl oz) | 2.6 tsp (0.43 fl oz) |
| Household bleach 6% | +3 ppm FC | 6.6 tsp (1.09 fl oz) | 7.8 tsp (1.3 fl oz) |
| Baking soda | +10 ppm total alkalinity (TA) | 11.2 g (0.4 oz) | 13.3 g (0.47 oz) |
Computed with our tested dose formulas. Granule scoops vary, so a small kitchen scale in grams is more accurate than guessing. Always follow the product label.
Daily dose
Test before each soak. Intex suggests checking every day at first, then at least weekly once you know your tub. Chlorine targets differ by source: the CDC says at least 3 ppm free chlorine for hot tubs, while Intex's support article lists 2–4 ppm. Keeping 3–4 ppm meets both. While soaking, stay at or below the swim limit on your chlorine label (4 ppm on many labels).
After a soak, top up to your target. Chlorine use depends on how many people soaked and for how long, so the dose changes day to day. The hot tub chemical calculator takes your reading and gives the exact amount. The hot tub chlorine guide covers liquid, granule, and bleach options in more depth.
One trade-off with dichlor: every 1 ppm of chlorine from it adds 0.9 ppm of stabilizer (CYA), which the CDC does not recommend in hot tubs because it slows chlorine down. In a small tub, it builds up fast:
| Chlorine used per day | 14 days | 21 days | 30 days |
|---|---|---|---|
| 2 ppm | +25 ppm | +38 ppm | +54 ppm |
| 3 ppm | +38 ppm | +57 ppm | +81 ppm |
That is one reason to refill inflatable tubs often. Using unscented bleach or liquid chlorine for top-ups adds no CYA.
pH and TA
Keep total alkalinity at 80–120 ppm and pH at 7.4–7.6. That range fits inside Intex's published range and the CDC's 7.0–7.8. Bubbles and jets drive carbon dioxide out of the water, which slowly raises pH over time. The default example above needs 5.7 g of dry acid (sodium bisulfate) to go from 7.8 to 7.5 in 250 gallons. Add pH products in small amounts with the pump running, and retest after 30 minutes.
Filter cartridges
Small inflatable filters clog quickly and are the first thing to check when water turns dull. Intex says to rinse the cartridge with a strong stream of water daily and after each use. It also says a cartridge lasts from a few days to about a week before it needs replacing. A Bestway Lay-Z-Spa manual likewise says to check and clean cartridges every day and change them weekly, or sooner if they stay dirty. Keep a spare set so one can dry while the other works.
The same Bestway manual recommends chlorine or bromine tablets in the chemical dispenser and says not to use granules. Other models and Intex manuals differ. Where your own manual gives a rule, follow it.
Winter
Freezing water can split an inflatable tub and ruin the pump. Some Bestway models include a freeze-protection mode. One Lay-Z-Spa manual says the heater must stay on whenever the water is below 42.8 °F (6 °C). Not every model is rated for cold-weather use, so check your manual before running it in winter. If you store the tub, drain it completely, dry it, and keep it indoors. When you set it up again, start with fresh water. The water change guide covers draining and refilling.
Safety
- Never mix chlorine products with each other or with acid, even in a cup. Add each one directly to the water, separately.
- Don't soak while free chlorine is above the swim limit on your label (4 ppm on many labels). Leave the cover open until it drops.
- Keep water at or below 104 °F. Limit soak time, especially for children and anyone pregnant or with a medical condition.
- Store chemicals dry, cool, and out of reach of children. If someone swallows a chemical or gets it in their eyes, call Poison Control at 1-800-222-1222.
- Always follow the product label. It is a violation of federal law to use a pesticide product in a manner inconsistent with its labeling.
FAQ
How much chlorine for a Lay-Z-Spa?
It depends on the model's water capacity, so check your manual. As a reference, for a 177-gallon Bestway tub, +1 ppm takes about 1.2 g of 56% dichlor or 2.2 teaspoons of 6% bleach. Multiply by the number of ppm you need to reach 3–4 ppm. Test before each use.
What chemicals do I need for an inflatable hot tub?
A sanitizer (chlorine such as dichlor or unscented bleach, or bromine), pH up and pH down, baking soda for alkalinity, and test strips that read free chlorine, pH, and alkalinity. Also get spare filter cartridges. Shock only as your sanitizer label directs.
Sources
- Intex, PureSpa Bubble Deluxe 4-person (210 gallons): intexcorp.com
- Bestway, SaluSpa Hot Springs AirJet 2–4 person (177 gallons): bestwayusa.com
- Intex Support, General maintenance for the PureSpa (chlorine range, testing, filters): intexsupport.com
- Bestway Lay-Z-Spa owner's manual (filters, tablets vs granules, freeze protection), via ManualsLib: manualslib.com
- CDC, Home pool and hot tub water treatment and testing: cdc.gov