Hot Tubs

A hot tub in the garden is definetly fun and is fairly low tech! I would say it has been one of my best purchases but it has led to other purchases. Getting into a tub of hot water and being able to relax and gaze at the night sky is wonderful, unless it’s raining or snowing or very windy 🙂 The practicalities compared to the “dream” are quickly brought to mind and with this in mind we considered building a “Hot Tub House” (large shed) but ended up with buying a small marquee (tent) to give protection from the elements and that actually cost more than the hot tub but hey ho 🙂 The tent offers protection from the sun so that the tub material doesn’t get “Sun Burn” and it means that we can get in the tub when it’s raining and still keep our robes and towels dry and it does offer the privacy factor. All things considered, a hot tub without any overhead and maybe side protection is not ideal.

The ideal situation for a hot tub is to have a “Hot Tub House”, which can be a large shed! Ideally it would have showering facilities because you should always shower first before using the tub, otherwise your tub maintenance costs and time spent cleaning will be significantly higher.

NOTE. A Hot Tub is not a BATH. You should always shower to remove body oils, perfumes etc before getting in the tub. I don’t recommend submerging heads under the water but if you want to, make sure you wash your hair before getting in the tub! The cleaner the tub users are, the less you will need to do with regards to “Tub Maintenance” and this will lower the cost of “Tub Maintenance”.

Tub Maintenance

If you’re a newbie to hot tubs (we all were at some point) you’ll be buying test kits and chemicals for this and chemicals for that, you’ll get completely overloaded with all the “expert” advice. Turns out that most of the expert advice comes from people that want to sell you chemicals! I’ve read so much stuff about hot tubs and how to maintain them and it has taken months to sort out fact from fiction.

This year we decided to go for the minimal chemical approach and forget about the “dubious” test kits and the chemicals for this and the chemicals for that and we have found that the water quality and clarity is just fine. All we are using is the slow release Bromine tablets in the floating dispenser and the addition of algicide every couple of weeks.

We use the tub 3 times per week at 40 deg C and drop it down to 30 deg C when not in use and we keep the filter running 24/7. If you allow the tub to get cold, you might find that you’ll get slimy deposits on the sides of the tub.

We change the filter once per week because there is only 2 of us and we always shower before using the tub. If you use it more often and have more people using it, change the filter more often and maybe increase the bromine tablets.

We rinse the dirty filter in running water and then leave it to soak in a solution of hot water with Oxygen bleach (that’s the “Oxi” powder that you use in the washing machine), washing up liquid and bio wash liquid. The filter is then is fully rinsed and dried before using in the tub. IMO, this removes all “bio” matter from the filter and seems to extend the life of the filters.

We check for a “bio film” every time we use the tub. A Bio Film is basically bio matter build up on the surfaces of your tub, if it feels slimy: you need to increase the sanitation e.g. use more bromine and possibly an extra dose of algicide. You will soon get to know how many of the the slow release bromine tablets to put into the floating dispenser. We sometimes have 4 tablets but usually it’s 3. If you only use one, you’ll need to use a “Starter” dose of quick dissolve bromine granules. The floating dispensers are usually considered to be a “maintenance” level dispenser but adding more tablets allows you to increase the overall level of sanitation.


1. We use Bromine instead of Chlorine because Bromine isn’t as harsh and can be re-activated so tends to be a lower cost overall and doesn’t damage clothing as much.

2. We have yet to try the Spagnum Moss sachets to improve the water quality and reduce the amount of chemicals. The science seems to be spot on but it’s one of those “extra” costs that you can probably manage quite well without.

3. Make sure that anyone using the tub has a good shower first, to remove deodorants and general “dirt”.

4. If you have any problems with the water quality and your tub holds less than 1000 Litres, just drain and start again.

5. The water in the tub can last several months but at some stage it will become “saturated” with chemicals and you will need to drain the water, clean the tub and start again. IMO, depending on the number of people using it and the frequency of use; Just drain, clean and refill every couple of months. Changing the water every month is not a hardship and will result in less chemicals.

6. Hard water can be a problem. This tends to create limescale deposits on the heater and generally cause problems with the circulation pump. Some people add salt to the tub to try to reduce the scaling but it is better to fill the tub with filtered water. You can do this initially for about £30 from places like Screwfix and you just need to change the filter periodically.

7. Heater and Circulating pump. These don’t last for ever and in hard water areas they don’t last much more than a couple of years. “Prevention is better than cure”. If your water supply is hard water, you need to decide about filtration.

8. Running costs, with regard to electricity. If your tub is 1000 L or less and you keep the pump running 24/7 and use the tub say 3 x per week at 40 deg C and have it at about 30 deg C when not in us, it will cost you between £7 & £10 per week. The main cost of electricity is the heating up of the tub. If you allow the tub to cool to “ambient temp” between uses, it takes longer to heat for ready for use.(some suggest the tub should be at no more than 38 deg C but I like 40 deg C). Depending on the heater, it might take it about 12 hours or more to go from say 15 deg C to 40 deg C.

9. Insulation is your friend. The more insulation you tub has, the longer it will stay hot and it will take longer to cool.

10. Bubbles! if your tub has a “bubbles” feature, it is likely that the heater will be disabled while you have the “bubbles” on. This cools the tub temp quite quickly.

Overall, having a hot tub is brilliant. The inflatable ones get the water hot and usually have bubbles, the more expensive ones have “Hydro jets” (which pump the warm water) and probably better filtration but hot tubbing is awesome.