How many people fit in your hot tub, and what to watch for when it's full

Short answer: the Q-tub Mini is for 1 to 2 people, the Q-tub XL for 4 to 6, and the Q-tub XXL for 6 to 8; with an internal heater, 1 to 2 fewer people fit than with an external one. When the tub is full, pay attention to four things: the water level (each bather displaces 60 to 80 litres), the temperature (which drops noticeably when the tub is full and the cover is off for a while), hygiene (shower beforehand and change the water sooner) and the weight on the base.

Capacity per model

With an internal heater, the heater sits behind a guard inside the shell and takes up one seat plus 100 litres; with an external heater, the full shell is available. More on this difference in wood-fired heater use and maintenance.

The water level with guests

Every adult displaces around 60 to 80 litres. Six people in a Q-tub XL means over 400 litres of displacement, and the waterline then rises by tens of centimetres. In practice:

• Fill the tub slightly below the usual level when expecting a full house, but always well above the heater connections.
• Keep the ball valve within reach to release water if it overflows; see also changing the water.
• Water that spills over the rim takes treatment product with it; check the pH after a busy evening.

Temperature with a full tub

A full tub cools faster: the cover stays off longer, cold air enters with every entry and exit, and cold bodies absorb heat. For an evening with lots of guests, allow for:

• Wood-fired: keep gently topping up the fire on a low setting during the evening; see hot tub heating time.
• Electric or heat pump: raise the setpoint by a degree and leave the heating on; see electric heating and heat pump.
• Between two groups: put the cover on for a bit, even just for a quarter of an hour.

Hygiene with many bathers

The more people, the faster the water ages: skin oils, sunscreen and sweat are the biggest contaminants. So:

• Have everyone shower before bathing; that halves the load on the water.
• After a busy evening: measure pH, check the filter and, if needed, do an extra backwash.
• With frequent turnover of guests, for example in a rental setting: change the water every 4 to 6 weeks instead of every 2 to 3 months, and never skip the weekly AquaFinesse dose.

Children in the hot tub

• Always under constant supervision; a cover is not a safety device.
• Shorter and cooler: 5 to 10 minutes at around 35 to 36 °C. Children overheat faster than adults.
• A booster seat or bench makes the tub more suitable for children, but takes up seating space for adults.
• With an internal heater: never on the heater side, and never let children pull on the guard.
• Babies and toddlers should not be in warm bath water at 38 °C.

Weight and base

A full tub is heavy. Calculate it for your model: empty weight plus volume in litres (1 litre is 1 kilo) plus bathers. A Q-tub XXL with an external heater: 200 kg plus 1400 litres plus eight people at 80 kilos comes to over 2200 kilos. The base must support that without settling; see preparing delivery and placement. A wooden deck or roof terrace only after the load-bearing capacity has been assessed.