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1 October 2020

How to use a hot tub

Get the most from your hot tub using our top tips on safety, maintenance and cleaning
Hot-tub-cleaning-equipment
Jade Harding

You’ve chosen the perfect hot tub, installed it without a hitch, and now it’s time to enjoy it. But alongside relaxing, you’ll also need to ensure you keep up with regular hot tub maintenance and stay safe while doing so.  

Our expert guide to using your hot tub covers everything you need to know, including how much it will cost to run, the chemicals you need to use to keep it clean, plus top tips on preventing leaks and cracks.

If you've just bought your new tub and need tips on setting it up, head over to our guide to how to install a hot tub

How expensive is it to run a hot tub?

Running costs will differ depending on a variety of factors, including the type of hot tub, size and how much you use it. That means it’s impossible to offer an accurate estimate of how much you can expect to pay.

Remember that it’s not just the extra energy you’ll be using; there are also the ongoing costs of water, maintenance and cleaning products. Again, costs for these will all depend on the tub, filtration system and the products you pick. 

The volume of water needed to fill a hot tub will make a difference to your water bill, especially if you're frequently refreshing it.

Does a hot tub use a lot of electricity?

If you’re using a medium-sized tub that fits around four people three times a week, you'd see an increase of at least £20-30 a month on your energy bill from the heating costs.  

But that's a conservative estimate – the costs can rise quickly if the hot tub is poorly built or your energy price plan increases.

Opting for a wood-fired hot tub will eliminate this issue, as most run totally off the wood in the heating stove, and not an electrical power source.

Eight ways to reduce your hot tub running costs

  1. Choose one that’s well insulated A poorly insulated hot tub will retain less heat and use more energy to keep the temperature up. Full foam and multidensity insulation are two of the most popular types.
  2. Use an insulated cover Around 60% of the hot tub's heat will escape through the surface, so ensuring your cover is well insulated, dry and in a good condition will help retain heat.
  3. Insulate the cabinet If your hot tub didn’t come with proper insulation, you can do a DIY job by adding wall insulation between the shell and the cabinet.
  4. Turn off the air valves Colder air can creep in through the air jet valves, so close them when you’re not using them.
  5. Check your electricity tariff You might be able to get a cheaper plan overall. Compare gas and electricity prices using Which? Switch, our independent energy comparison website.
  6. Clean the filters A dirty or clogged-up filter will force the tub to work harder to stay clean. Keep up with regular filter maintenance to reduce energy costs.
  7. Opt for a smaller tub You'll have less water to heat and fewer features to power.
  8. Keep it in an enclosure or surrounded by shrubs The warmer the outside air temperature, the less energy your hot tub will use to heat up.

How long does it take to get a hot tub hot?

A good quality, medium sized, hard-shell hot tub should heat up by around 3-6°C per hour. Larger or poorly insulated tubs could take longer.

Inflatable hot tubs have less insulation and low-powered motors, which means they take longer to heat. 

Wood-fired tubs warm up pretty swiftly (in around three hours).

Other factors that will affect the heating times include:

  • insulation quality
  • outside temperature
  • the size of the tub
  • temperature of the mains water
  • how powerful the motor is
  • keeping the cover on while heating
  • when you last used the hot tub.

Most of the time, you should only be topping up the heat of the water in your hot tub. If you’re starting from scratch, here are some average heating times for different types:

How to clean a hot tub

You should wipe around the tide lines of your hot tub after every use, and do a more thorough clean and water change every three months.

Here’s a step-by-step guide to cleaning your hard-shell or inflatable hot tub:

  1. Flush out the pipes using a pipe cleaner Follow the instructions, but this will need to be added around an hour before draining the tub.
  2. Drain the hot tub Turn the tub off completely and open the drain valve. You can either let it drain where it is, or attach a hose to lead the water to lower ground.
  3. Remove any debris or dirt
  4. Wipe down the cabinet, shell, jets and cover You'll need products designed for hot tubs and a soft cloth. Regular household cleaning products can affect the pH levels and damage the shell.  
  5. Refill the hot tub Make sure the drain valve is closed and everything is in place. Then position your hose in the filter area and begin to refill. Filling from there will make sure the pump fills with water first, preventing air locks when you turn it back on.
  6. Turn the power on Only do this once it's filled up.
  7. Heat and re-balance Let it heat to around 20°C, then balance your pH and add your sanitiser.

Your hard-shell hot tub will also need to be serviced once a year.

How to clean a wood-fired hot tub

Wood-fired hot tubs are used a little differently. Most people will empty and refill their tub after every two to three uses.

Each time you do, you should drain it completely, wash the inside and outside with a hose and soft cloth, and empty the ash from the stove using a shovel.

You also need to treat the wood once a year to keep it good condition. The treatment will differ depending on the wood your tub is made from, so check your manual for details.

How to clean a hot tub filter

The filter in your hot tub plays a crucial role to keeping the water clean and the entire hot tub system running smoothly, so it’s important to take care of it.

All hard-shell and inflatable hot tubs will have a filter that will need to be cleaned weekly. Turn the tub off, remove the filter, spray off any dirt or debris with a hose, dry the filter and then put it back in.

For hard-shell tub filters you can also do a deeper monthly clean using a filter solution. 

Filters for inflatable tubs need to be replaced monthly, but hard-shell hot tub filters won’t need replacing for more than a year if you take care of them.

Wood-fired hot tubs don’t typically come with a filter; however you can buy and install one separately if you’d prefer one.

Can a hot tub or spa be left unused for a long time?

Yes. You can leave your hot tub or spa unused for a long time, but you’ll need to take some precautions to ensure it doesn’t get damaged.

For hot tubs being left unused during winter, or in areas where temperatures dip below freezing, you’ll need to prepare it to ensure that it doesn’t freeze.

  • Drain the hot tub completely, including all the plumbing.
  • Remove the filter, motor and any pumps that you can, and store in a warm, dry place.
  • Suck any remaining water from the jets.
  • Cover any open pipes with mesh.
  • Fit and secure the cover and wrap with tarpaulin for extra protection.

In places where it’s unlikely to freeze, you’ll still need to drain the tub and keep it covered while it's not in use, but removing the motor, filter and pumps won’t be necessary.

Hot tub chemicals: keeping them topped up

Keeping the chemicals in your hot tub topped up and balanced is crucial. The most important chemicals that all hard-shell and inflatable hot tubs need are pH levellers and a sanitiser, such as chlorine. But there are also plenty of other products that can help to keep the tub running smoothly.

Sanitiser

A chlorine or bromine level of 3-5 parts per million (ppm) must be maintained in a hard-shell or inflatable hot tub at all times. To keep to this level you should add sanitiser and test every one to three days that your hot tub is in use, using a test strip.

Every time you add the sanitiser you’ll need to wait an hour and test the levels before you get in. If you've over-chlorinated your hot tub you can either let the levels drop by themselves, refill the tub or use a chlorine neutraliser.

Sanitisers come as granules or tablets. You'll need to add the granules manually, while tablets go in a floating dispenser.

You should also give the water a quarterly boost of sanitiser to keep it hygienic. Add 60g of chlorine granules per 1,500 litres of water, then wait for the levels to drop.

Wood-fired hot tubs don’t typically use these chemicals, but instead require a weekly top-up of a non-chlorine shock oxidiser.

If you’re setting up a new tub, then the process is slightly different – head over to our guide on how to install a hot tub to find out more.

Total alkalinity and pH levels

When you add and test your sanitiser, you should also test the total alkalinity of your hot tub water and balance the pH levels.

The total alkalinity should be 80-120ppm, with a pH between 7.2 and 7.8. A low pH can lead to itchy, dry skin, and can also damage the hot tub shell, while high levels can cause scale build-up and cloudy or foamy water. Unbalanced levels either way can also reduce the effectiveness of the sanitiser.

To raise the alkalinity in your hot tub, you should add sodium bicarbonate (baking soda) or any other type of alkalinity increaser. To lower acidity levels, use a reducer.

Shock treatment

Alongside your sanitiser you should also use a shock treatment once a week, which will break down waste that can't be filtered. If you have a wood-fired hot tub, you can use non-chlorine shock oxidisers.

No-scale product

The total hardness refers to the levels of calcium in your tub. Test for this every one to three days – if it’s too high you’ll find scale around the shell and cloudy water, and it can start to damage the internal parts of the hot tub.

The calcium level should be around 100-250ppm. If it’s higher than this you need to use a no-scale treatment. This won’t reduce the hardness, but it will stop the damage.

How long can you stay in a hot tub?

General guidance from manufacturers says healthy adults who are not pregnant can stay in a hot tub heated to 37.8ºC for around 15-30 minutes at a time. Any longer and you risk overheating and experiencing symptoms such as light-headedness, dizziness, or nausea.

If you’re pregnant, you should avoid excessive heat because of the higher risk of overheating, which can be harmful to the baby. The NHS advises avoiding them completely, saying: ‘If you're using a hydrotherapy pool, the temperature should not be above 35ºC. Some hot tubs can be as hot as 40ºC, so it's best to avoid them.’

US-based industry body the Pool and Hot Tub Alliance also states: ‘Infants and toddlers should not be permitted in a hot tub at all as babies' thin skin makes them more susceptible to overheating.’ It's recommended that older children should limit their use to just five minutes at the highest temperature (40ºC) and 15 minutes at a lower temperature (37.8ºC).



If you have any medical conditions you're worried about, always consult with a healthcare professional before using a hot tub. 

Stay within the safety guidelines and you can use your hot tub every day.

When UV levels are high, make sure you're protecting your skin, too - here are our sun cream reviews

Hot tubs and health: your questions answered

  • What are the health benefits of a hot tub or spa? The warm water widens blood vessels, which aids blood circulation. It can reduce swelling, loosen muscles and offer relief to painful joints.
  • Can you go in a hot tub when pregnant? The NHS advises that pregnant women avoid hot tubs.
  • Can babies go in hot tubs? No.
  • Are hot tubs full of germs and bacteria? Not if you maintain them properly and keep the chemicals topped up. However, pseudomonas (can cause rashes) and legionella (which can cause Legionnaires' disease) are two types of bacteria that can bypass disinfectants and live in certain areas of hot tubs.
  • Should I shower before and after the hot tub? Yes, showering before will remove any sweat, dead skin cells and skincare products, reducing the work required from the filter and avoiding upsetting the pH balance. Showering afterwards will get rid of any chemicals left on your skin.
  • Can a hot tub kill you? Yes, in rare cases sitting in warm water for a long period of time can cause serious and even fatal heat-related illnesses.
  • Can hot tubs damage your lungs? Yes, in rare cases you can catch Legionnaires' disease, which causes lung infection, from breathing in droplets of water in hot tubs.
  • Are hot tubs bad for your heart? The British Heart Foundation states: ‘If you have a heart condition or have high blood pressure, it is generally advisable not to use spa facilities – including baths, saunas, and jacuzzis or steam rooms. Sudden changes in temperature can put extra strain on your heart and circulation. Before doing these activities, have a chat to your GP.’
  • Can you go into a hot tub if you have a pacemaker? Talk to your doctor. It shouldn’t do any harm to your pacemaker, but it may not be safe with your underlying medical condition.
  • Can you get chlamydia/an STI from a hot tub? No.
  • Can a hot tub cause a UTI? Pseudomonas bacteria can, in rare cases, be found in hot tubs, which increases the risk of a urinary tract infection.
  • Are hot tubs good for blood clots? In some cases, a hot tub could help to reduce the size of a blood clot and prevent growth, but it can also do damage. Always speak to your doctor first.
  • Can hot tubs cause headaches? Hot tubs can cause dehydration, which can then result in a headache. Don't stay in the water for longer than the recommended time, to avoid dehydration.

Hot tub repairs

A good-quality hot tub that's been well taken care of should last for 10 years or more. However, inflatable hot tubs, or models that are poorly made and aren't maintained, typically won’t last as long.

Knowing how to do simple repairs will also help to lengthen the lifespan of your tub.

How do you mend hairline cracks in a hot tub?

  1. Turn off and drain your hot tub.
  2. Clean and dry the damaged area with a soft cloth.
  3. Apply the repair material from an acrylic repair kit for hot tubs, using the instructions on the packaging.
  4. Allow it to dry.
  5. Sand down, buff and clean the area.
  6. Refill your tub and check for leaks.
  7. If it’s still leaking, you’ll need to drain and start again.

How do you stop hot tub leaks?

The first step to repairing a leak is switching off the tub and locating the leak. Leaks will typically come from the pump. Other places leaks can occur, and ways to fix them, include:

  • light fittings: tighten fittings or replace them
  • filter: tighten fittings, new gasket or new housing
  • plumbing pipes: tighten fittings, new gasket, re-glue worn joints, seal minor cracks in pipes
  • the shell: minor leaks can be fixed with acrylic repair kits.

Before doing any work yourself, check your hot tub's warranty. If it’s in warranty, ask the manufacturer to deal with the leak – trying to fix things yourself can void your warranty.

How do you repair an old hot tub cover?

There are plenty of DIY repair kits in shops that will patch up minor rips and tears on the vinyl top of a hot tub cover. If there are numerous rips, then it might be worth replacing the entire top of the cover – but only if you can get hold of marine-grade vinyl.

Replacement straps are also widely available if yours have worn or broken.

If your hot tub is beyond repair and you want a new one instead, head to our guide to how to buy the best hot tub