Avoid these 7 DIY Hot Tub Mistakes

Avoid these 7 DIY Hot Tub Mistakes

When I built my own DIY Hot Tub, what seems like a lifetime ago, I made every mistake possible. I’ve said more than once on this blog, and my YouTube Channel that because of this, I am more than qualified to advise others on their DIY hot tub builds.


Today, I’ve had the pleasure of helping over 700 of you with your builds in the shape of plans, build consultancy and parts. It’s a real privilege to be involved with some of the fantastic hot tub projects that dream up.


In this article, as we head into peak building season, I am going to highlight the 7 mistakes that I think you should avoid when you are building your own DIY Hot Tub

DIY Hot Tub Mistake #1 – Size


The best DIY Hot Tubs are not necessarily the ones that are the size of an Olympic swimming pool! My top tip here on what to avoid is something that is too big or too small.


This may sound simple right? Well, you would be surprised. Put some thought into the actual size that you need rather than the size you want.


Let me explain.


If you make your hot tub too big, then you can run into issues with running costs due to the heating. More water means more energy to heat up = more cost.


A larger body of water will also be a lot slower to heat up so this can affect how you use your tub – you have to plan the use rather than be able to use it ad-hoc.


This was one of the things I got wrong in my initial planning. I was going too big. Luckily, “Pool Man John” reigned me in so that I ended up with something that was much more useful and economical to not only build but run.


Don’t let your ideas get away with you, work out how many people you want to have in the tub and how much space you want for each – then you have the size you need. Makes sense, I am sure.


#2 Space


The mistake involving space is never to do with the tub itself. It is to do with two other things. Firstly, the control room – one of my favourite topics on this blog.


Not leaving yourself enough room for the control room is a mistake. Trying to make plumbing joints in a confined space is difficult. Trying to service your hot tub kit in a confined space is even more difficult.


Leave yourself plenty of room for the control room. Plan it. Lay the kit out. Make sure you have enough space and you will thank me when it comes time for changing a filter or servicing the pump – your life will be so much easier!


The next space mistake I see revolves around the cover. What are you going to do with the cover when you are in the tub? Where are you going to store it? You don’t want to just be tossing it onto the lawn or patio. Think where you are going to store then when you are in the tub itself. You’ll thank me for this one 😉


#3 Planning


Fail to plan then plan to fail is the saying, I think. The number of “half way through rescue projects” that I pick up each year is phenomenal.

The sheer number of people that rush into a project without the right plans in place – it is just a disaster.


I’ve picked up projects that have pipes through the walls then they have stopped as they realised they have no idea what to do. I have picked up projects where the wrong size pipe has been used and they are wondering why there is next to no flow on their jets.


You absolutely must have a plan in place before you start. The more you plan, the more likely you are to succeed in building that dream hot tub.


Planning is certainly something I can help with – more info and actual plans are here.


Get it right from the start!


#4 The Lights – don’t do this!


This is still my favourite – only because it personally cost me $1000 in electronic circuit boards. I did manage to get some back through RMA – thanks to “Pool Man John”


Whatever you do, do not plug your swimming pool grade LED light that you are going to use in your DIY Hot Tub directly into the spa pack – it will blow the circuit board.


The circuit boards on most spa packs whilst they have a 12V out (quite often AC, NOT DC FYI) the current that is allowed to be drawn from these connections is so low. Like 0.25A low – not 3A like a regular LED swimming pool light that is 35W for example would draw.

This killed my first DIY hot tub experience, even more so when I didn’t know what was wrong. The kids were already in, I had just switched on the jets, the blower and the light, it worked for about 5 seconds then the whole thing was in darkness. Fuse had blown, spa pack was dead. I had no idea what the problem was. I could have cried (I almost did!)


It took a couple of engineering friends of mine to look over what I was doing and the circuit diagrams to work it out for me – that’s what friends are for right!


Well, you will be pleased to know that in order to avoid this, I actually invented a connection kit that allows you to plug a pool light into a spa pack. It is one of a kind – there is only me that makes them 


And, there is only one LED light that comes with one – mine! Check it out here.



#5 Electrics – read and configure!


Not known as being one that reads a manual, it does pain me to say this, but you need to read the manual.


Getting the electrics wrong can be a problem.


Firstly, especially if you are in the USA, you need to get the voltage right – you need 230V not 115V.


Secondly, you need to configure your spa pack to tell it that you are giving it 230V and not 115V.


Thirdly, you need to make sure that you are plugging the equipment into the right place – so many times (I actually had one this week) a pump is plugged into a socket for a blower – this is one of the reasons it does not turn on.


Lastly, you need to program your spa pack to tell it what you have connected – it does not know. For example, the chances of it shipping from the factory, “knowing” that you are going to plug in a circulation pump, a single speed jet pump and a blower is slim – you need to configure this. Don’t configure it and strange things happen when you turn on the electric – pumps and blowers don’t work how they should.


Read the manual!


#6 – Heating


This is definitely a new addition to my list. In the economic times that we are in, April 2023 at time of writing, things are somewhat of a mess when it comes to costs of energy.


It varies from country to country – in the UK from example, electricity has gone through the roof.


Whereas almost every tub that I designed a few years back would be electric and spa pack heated, that is certainly not the case anymore. In Europe, pretty much all of them are Air Source heated and at the moment, in the USA the most popular heating method for my customers is gas or propane.


You need to select the heating method that is going to work for you and how you plan to use the tub, but also your budget!


I have an extensive post here on the options


#7 – Time – Rome wasn’t built in a day!


And finally, yes, Rome wasn’t built in a day as the popular saying goes. Neither is a DIY hot tub. The project will take longer than you think.


I often get asked, how long will it take – this is very much a how long is a piece of string. However, I would say on average 10-12 weeks is normal for a project like this. Really depends on what time you have available and the man power too.


What I will say here is don’t rush. Take you time with every aspect, especially the plumbing.


It is no secret I have flooded my control room twice! Yes, twice. The second time, I found a 90 degree elbow in the control room that had no PVC pipe cement on – dry. I was clearly rushing that day, and it ended up costing me a new pump.


Take your time, enjoy every stage – it is so worth it in the long run


Happy Hot Tubbin’



Can I Help You?

If I can help you in any way I would love to hear from you. You can get in touch using the form below.

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

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