Pumps, Blowers, Filters & Ozone – Essentials for a DIY Hot Tub

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Pumps, Blowers, Filters & Ozone – Essentials for a DIY Hot Tub

Pumps, Blowers, Filters and Ozone, pure essentials to any DIY Hot Tub build. In this post, we are going to look at these specific components in detail and more so about why I chose the components that I did. Hopefully, this will help you with your own purchasing decisions when you are designing your own DIY Hot Tub.

We’re now getting to the expensive components of your DIY Hot Tub so it is worth taking some time to get all of this right. Let’s start with looking at pumps. Once you have decided how many jets you are going to have, you can then make a decision on the pump that you need. I went with 15 jets so opted for a single 3HP dual speed pump so this pump will take care of the circulation of the water as well as powering the jets.

If you are going for multiple pumps, you need to make sure that the Spa pack that you choose can deal with them too. Unless you have some real grand design I would suggest going for a single dual speed pump. It makes life simple and the plumbing is easier. What I can say that for my 2.6 (8.5′) x 2.5m (8.2′) Hot Tub, 2800 litres (616 gallons) of water and 15 jets, the 3HP pump is more than sufficient. I opted for a Waterway model as this was well priced and a good brand.

DIY Hot Tub Control Room

DIY Hot Tub Control Room


I did think that I would try and not use a blower and just use a Venturi system but I am glad that I didn’t the blower makes all the difference.

There are different types of blower as you would expect. I opted for a 500W single speed blower that does do some heating of the air too. I wont describe the analogy that I received from John (the pool supply guy) on the benefits of blower heating the water, but I’ll summarise in that it will not make any difference at all.

What it will do is create lots of bubbles for you – perfect! If you are looking at a multi-speed blower again you have to match this with a Spa Pack that is going to be able to cope with it. As you would expect, the more features you are looking for, the more they cost.

The filter

This is essential to keeping that lovely large body of water nice and clear of debris and bits. With the filter, these are sold by how many litres an hour can flow through it and also the size of the body of water you plan to filter. The bigger your hot tub, the bigger the filter required. Makes sense really. Filters are made up of four elements, Cores, Media (Filtration Fabric), Bands, and End Caps.

What you want to do is make sure that the filter has a properly designed core that maximises the filtration area. This in turn increases the flow and it will also create a uniform flow through the entire cartridge. What this means is that you will in effect increase its life and the cleanliness of your Hot Tub water. Top tip, don’t skimp and buy cheap here. Buy a good quality filter from a reputable manufacturer.

When you are choosing your filter, you need to be mindful of the pump that you will be using too. I choose a Waterway filter and a 50sqm one. That matched up with the size of my Hot Tub (internal measurements 7.5ft x 6.2ft approx) 46.5sqft. So on those calculations I am at the upper limit of the filter really once you allow a little bit for water head.

However, one of the features of the Waterway filter that I chose was that it had an auto bypass for high pressure. This means that under regular circulation pressure it will filter my tub. When the 3hp pump kicks in and the pressure increases, it will bypass some of the the filtration to increase the flow and stop the potential damage to my pump.

From what I have found online, over specifying your filter is not a bad thing and it can reduce potential expensive damage to your pump if the pump us put under undue pressure due to a restriction of flow through the system. So, if you are not sure, then you can go up to the next size if you need to.

Ozone or Ozonator

The Ozone or Ozonator was the part that confused me and also is the only part that did not to to work on my Hot Tub; let me explain. What the ozonator does is generate ozone gas that is drawn into the water through a Venturi effect in your plumbing. Ozone kills all the nasty stuff in your hot tub and is great for keeping your hot tub clear and disease free.

The mistake that I made with the ozonator was that the way I plumbed it in made that there was not enough flow and thus Venturi draw for the ozone to be drawn into the water when the tub is just filtering – ozone doesn’t work when the jets are running. If you are going to use an ozonator then you have to plan for this in your plumbing and also make sure that you are going to have enough water flow to draw the ozone into the water.

I got this bit all wrong and ended up cutting it our and re-plumbing around it. Have a look at the diagrams below to see why. The tub works just fine without it and making sure the rest of the chemicals are all balanced I’m sure I have disease free water too.

If you are thinking of adding one of these just save the money and don’t bother. It was a total waste of time for me, leaked everywhere and ended up being thrown in the trash without ever working properly. That was a good £120/$150 well spent!

The Spa Pack

The Spa Pack is really the control centre for your Hot Tub. It is the part that controls the blower, the heater, the pump the lights and the ozone too. As you can imagine, it is pretty important. There are a few things that you need to consider when you are selecting your Spa Pack.

Firstly, is the heating element and the power of the heater. The heater that you need is going to be dictated by how much water you are looking to heat. I’ll use my own example here and I have 2800 litres (616 gallons) of water that I need to heat.

When I was designed the original tub and in the planning stage, I was designing it to be slightly bigger than I have now and I calculated that I would have 4000 litres (1057 gallons) of water. John the pool man was suggesting as I have mentioned earlier a custom built heater that would be 12KW to cope with the volume.

You do not want to do this at all. Its incredibly expensive, I think it was in the region of £9000 ($14 000) just for the heater and then there is the running costs on top. Not to mention time to heat.

DIY Hot Tub Spa Control Pack

DIY Hot Tub Spa Control Pack

My tub at 2800 litres (616 gallons) is quite large and it does take time to heat. I opted for a 3KW heater and from cold, it takes 40 hours to heat. To recover, which is after you have used it, how much temperature you loose, I’m looking at 0.5 degrees an hour.

When I’m using the tub, if I’m in for an hour, I’ll loose about 3 degrees so it is a further 6 hours to heat it back to temperature.

Now, if I wanted to speed this up, I could have put an independent thermostatically controlled slave heater in and double the size to 6KW of heat which would in turn speed things up. I think fluid dynamics is not a straight line so I will not say that it would be twice as quick but it would speed things up.

These are the again decisions you need to make at design stage or leave enough space at design stage so you can retro fit if you need. I’m fine with the 3KW and now that I know how long things take I can plan accordingly.

After the heater portion of the Spa Pack, the next decision that you need to make is whether the spa pack is able to deal with the individual components you have selected.

For example, if you want a separate circulation pump and a pump for the jets, then you need the ‘slots’ on the Spa Pack to plug them in. Blowers, Ozone, all need to be plugged into the spa pack so it is very much a case of trawling through spec sheets to make sure that it is capable of what you want.

For me, the absolute must was WIFI control. I love gadgets in general but from a practical side I wanted to be able to control the spa from afar. Set it heating up if we are away and monitor the temperature.

I knew that I wanted a Balboa Spa Pack and opted for the WIFI enabled BP601.For the topside controls, this really depends what you want. I know that some people now don’t bother with them and just use the WIFI.

I however did want some control just in case the App or WIFI had any issues and went for the TP400 a simple but does the job control. I can’t stress enough to look at the specifications as I’ll explain shortly how my not paying attention to specs has cost me in the wallet.

The “Control Room”

The “Control Room” as I call it is where you need to house your pump, Spa Pack and filter. If you decide to go with them, the Ozone and the blower will also be housed in this area. The first thing that I would say here is measure up the space that you think you need for these components and then double it!

This is one of the things that I would change on my own tub if I came to build it again, I would give myself more space. The problem that I had was firstly, it was too small so I needed to increase the size mid-build, not ideal!

Secondly, it is still a little tight and not deep enough for the filter. I have my filter tilted on a slight angle so that it fits in and the plumbing that comes in from the bottom drains of the tub are also on a strange angle when they attach to the pump inlet. If I had more space, this would have made things easier.

I have the space on the deck near the tub, I think at that stage of the build, I’d dimply had enough of digging! I mentioned in other posts that I had to dig by hand so after a couple of weeks of lugging earth around, I was done and rushed that part a little.

DIY Hot Tub Control Room

DIY Hot Tub Control Room

The next thing for the “Control Room” is make sure it has a drain! You don’t want this to fill up with water (believe you me, I’ve don’t it and it is not pretty) The expensive components are meant to stay dry – fact! You need to make sure that your Control Room can drain if water does escape, which it will, when you change the filter or when you remove the pump for a service.

It needs to drain away. I put a piece of pipe in the bottom of mine so when I lined it with concrete, I removed the pipe once it was dry and there was a hole onto the dirt for the water to drain away. I know some people also put in a water pump with a floatation switch into the control room so if it does fill up, the pump will kick in. This is fine, but it depends just how quick things fill up.

I said that I made some mistakes on my build that this website would help you avoid and this was one of them. Six weeks following the “launch” of the hot tub, despite my electrical issues, I thought things were going well. One Sunday afternoon whilst watching the F1 (Yes, I have installed a TV but we’ll come onto this in some later posts) suddenly the power went. Having had problems with the light already, I thought it was that again. The MCB had tripped in my garage so I turned it back on, booted up the spa pack and as soon as the pump kicked in, it tripped. I thought that I had better have a look what was going on in the Control Room to find that it was full to the brim with water. “Oh S£££” I think was my reaction as I thought that the block work on the tub had cracked and it was a leak. After draining the Control Room and starting to faulty find, much to the amusement of my daughter when I was drenched by the pipe that had come loose – somehow, I had managed to leave a dry joint and not glued in that section – a time bomb waiting to happen.

What is the point to this story I hear you ask. Well, drainage of your control room is key as if you do flood it, like I did, you want it to empty. Secondly, even if I had installed a “flood”pump, because the pipe came loose and my 3HP pump on full speed was essentially filling the Control Room, my money saving tip here would be don’t bother.

In my case, a secondary “flood pump” would have been useless because it would not have emptied the Control Room quick enough. Did I damage anything? No, luckily, I did not but it took a lot of time to take things apart, drain them of water and dry them out. Even the pump, I had to disassemble the pump right down to the coil and tip out the water from the ‘dry end’ not ideal. I was lucky.

Hope you enjoyed this weeks post.


By |2021-05-06T16:27:28+00:00January 31st, 2020|Build A DIY HOT TUB|Comments Off on Pumps, Blowers, Filters & Ozone – Essentials for a DIY Hot Tub
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