DIY Infinity Hot Tub – this was what Brian wanted when he got in touch with me back in April of 2022. Unlike most clients that make contact as they dont want to pay the exorbitant prices that the spa and pool builders choose, Brian has somewhat of another problem.
Where he wanted to build his infinity hot tub at his new home that was under construction in the Bahamas – there simply were no pool or spa builders. Therefore, Brian wanted to use his existing contractors to do the work.
The other problem, was that they have never built one before. This is exactly what I do, so was more than happy to start initial dialogue with Brian for how I could help him and the team.
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Where it started – DIY Infinity Hot tub
So, to get things started, Brian send me a picture of a load of sand and the view that he wanted to frame with the hot tub. This was going to be one amazing tub when it was completed, just needed a little bit of vision to get it going.
The Concept – DIY Infinity Hot Tub
I drew up a concept for Brian and as I do with all my custom clients, we go back and forth with the design until they are happy. Brian knew what he wanted so it didn’t take us very long to get the concept done.
As with all projects, turning that concept into reality is always the challenge.
With the designs complete, it was over to the guys to start clearing the area. I am not going to post pictures of piles of sand, but like any DIY hot tub, this infinity tub needed to have a base. To lay the base, they needed to get down to rock so that they were not building on sand. From there, they built up so that it was at the right level.
Brian and the team had opted for a poured form. This was the same method that they had used to form up the walls of his new home so they knew what they were doing. This was going to be a little bit different as they needed to get some plumbing into these walls first which is exactly what they did.
Forming up to the walls
When you are forming up for a hot tub or an infinity hot tub, then you generally do the pour in sections. A couple of times I have had clients do what is called a mono-pour where you pour the whole thing in one go, but this is not normal. Basically, it is a lot more difficult to do, so the concrete guys tend to have experience doing this. If you are mixing things up yourself in a manual mixer, then you are not going to be doing a mono pour.
So, what the team did was pour the base. They they poured the outer walls and then it was onto the inner seating. With the inter seating, what they did was used crushed rock and aggregate to fill the void in the seats. It is a good idea to do this as it is a lot cheaper than filling it with concrete! Concrete is not the cheapest of materials, so having a reduced volume is the way forward – put some of those dollars back into your pocket.
Forms complete – DIY Infinity hot Tub
You can see here what the DIY Infinity hot tub was beginning to look like once the forms had been removed. It was taking shape nicely.
Waterproofing the DIY Infinity Hot Tub
With the walls in place, cured they were ready for the next stage of the process which is the sealing and waterproofing. What I normally suggest is that concrete forms or rendered concrete surfaces are sealed first. You can do with what a PVA wash which is builders PVA glue mixed with water so that it can be painted into the surface. This is a cheap and easy way of sealing the surface.
From there, it is time to get the waterproofing layer into place. Depending on where you are located, there are different brands of product. In the USA, I like the Hydroban product from Latticrete. In Europe, Ardex S7 plus is a great material. These are not cheap substances, but in my opinion they are the best for the job.
Once there is a couple of coats of the waterproofing layer, the next stage is for the tiles to be added and you can then start to see what the final “product” is going to look like.
At the same time the tiles were being done, it was time for the team to turn their attention to the control room.
Brian has a huge veranda deck looking out to sea and underneath is a storage area that they are going to use for the control room. It is out of the elements and also below the waterline so it is a perfect location.
As this is a DIY infinity hot tub, they need to have a balance tank for the overflow. They way in which a DIY infinity tub works is that when it is full, there should be water right up to the lip of the overflow. There also needs to be a store of water that can be returned to the hot tub to make it overflow when there is nobody in the tub.
This is the role of the balance tank. To store water and then have the pump return it to the tub when it is not needed. So, for example, if 2 adults jump into the tub, they will displace 70 litres or 15 gallons each – that water needs to be stored. So, when they get out, it can be returned to the hot tub to make it overflow. Quite a straight forward process when you think about it. There just needs to be some calculations done for the size of the balance tank.
Brian’s balance tank is located in the control room and the water is caught in a trough then fed by gravity back into the balance tank. We put an auto top up in there and an overflow too as the Bahamas are renowned for a monsoon-like climate so can get a lot of rainfall. That would fill up the tub, and the balance tank too if there were no overflow installed.
Brian’s control room also has auto dosing salt system and UV for added clarity – Brian’s goal was to have as little maintenance as possible to do on the tub.
The Finished Product
With the tiles in place and cured, it was time to fill the tub. Brian had the water delivered so that it was filled quicker. There of course were the usual leaks that you have when yo do your first fill, this is totally normal and happens to everyone.
Simply WOW! How good does this look?
I would like to say that DIY Hot Tubs, whether they are infinity tubs or not always go to plan and there are no problem – quite the contrary – there are always teething issues.
Brian had some pretty large air locks at first after filling his tub which we needed to get rid of.
He also has a problem with the water draining back into the balance tank when the pumps are not working. This is because they are below the waterline and his team forgot to put in the Hartford loop for the hot water returns. So, what happens is the water drains back into the balance tank and then out of the overflow.
A good quality one way valve from Jandy, Hayward or Pentair (swimming pool part) will fix this – but being the Bahamas, you can’t just pop down the local pool store and pick one up. Brian did try to retro in a Hartford loop but it is just too low and they still have the problem of the draining. He keeps his circulation running 24/ at the moment as a temporary measure.
Brian, thank you for all the pictures and video – it has been a total pleasure working with you on this project and I have thoroughly enjoyed it.
Happy hot Tubbin’
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Thanks - Andi
Hi, Andi here. I own Buildahottub.com and also write all of the articles and info pages on the site. Some years back now, I built my own hot tub but struggled to find the information I needed. So, once my tub was complete, I started this website to help others in their own pursuit of hot tub and plunge pools DIY building information.
Today, I've helped over 1000 DIY customers just like you all over the world build hot tubs and pools. Have a good look around the site, there are lots of resources here. Please do get in touch if I can help you. - Cheers, Andi