Can I use Pool Parts on a Hot Tub?
Can I use pool parts on a hot tub build? This was a question that I was asked this week by a visitor to the website. I thought that it was such a good question that I would write a post about it. I’ve done this for a while now so what is really encouraging is when you get a question that you haven’t been asked before.
Pool Parts Vs Hot Tub Parts
I am going to preface this section with the point that I am talking about existing hot tub setups here. Not new builds – I will cover these later in this article.
In general, pool parts and hot tub parts do not mix. What do I mean by that. Well, for example, you would not want to use a sand filter on your existing hot tub setup. Why? Because the flow rates of sand filters and about 1/3 of what is actually needed to power all your jets. This is true for pre-filters, pool returns which cant be used as jets and pool drains. All of these do not have the flow that is needed for a hot tub.
Regular readers of the blog or my YouTube Channel will know that I always talk about each jet needing 10GPM of water flow. 16 jets, 10 x 16 = 160 GPM. This is what the pump needs to deliver to the hot tub plumbing after head height and resistance.
If you take some regular pool parts like sand filters and pool drains, their flow rates are around 80 GPM, that means before friction and head height, we are at half what we need int terms of flow to power the jets.
Therefore, to conclude this section, pool parts on a hot tub are not a good match. However, we will look at how we can use some pool parts successfully below and we will even look at how on a new design, we can make use of pool parts in their entirety.
Pool Parts that you CANNOT use on a Hot Tub
This is quite a short section as I have already touched on this above. You should not be looking to use pool sand filters, pre-filters, pool returns as jets and pool drains on your existing hot tub. They will not work and could damage the pump by causing it to overheat by not having the correct flow going through it and providing additional resistance.
Pool Parts that you CAN use on a Hot Tub
Pool parts on a hot tub that you can use? Most definitely the skimmer. If you are building a hot tub outdoors then you are going to want to use a skimmer. They are ideal at collecting debris off the surface and help with water flow into your pump and filter.
It is also possible to use summing pool automation systems. Systems from companies like Jandy, Hayward or Pentair have been designed so that they can be used for Hot Tubs too. Essentially, just like a traditional Spa Pack, they are a set of fancy relays with a control panel. Hooking up your dual speed pump, turning on your hot tub lights and air blowers are all possible with a swimming pool automation system.
Given the cost of a swimming pool automation system, you are probably better off sticking with a regular spa pack and maybe adding a WIFI module if you are looking for cell phone control. The result is very similar and arguably a lot easier to setup. That said, it may make sense if you are combing things like chlorinators and using external heating systems like gas or propane heaters on your hot tub.
How to use Pool Parts on a Hot Tub
This section of the post may seem somewhat contradictory to the rest of the article. However, it is important to note that this section only applies if you are designing a brand new hot tub build. In your brand new hot tub build you are going to have total control over the plumbing setup and this is what we are going to look at now.
Dedicated Plumbing System
Whilst I have already mentioned that you can’t use Sand Filters or Pre-Filters in a regular hot tub setup due to flow restrictions, there is a way to make these parts work for you. The way that you would do this by creating a separate circulation plumbing setup.
How would this work?
Firstly, you would need to have two dedicated lower inward flow drains. You would then need to have a dedicated circulation pump. On this plumbing loop, we are going to have, just for this example, lots of pool parts. We will start with a pre filter that will follow the pump. Then, we will have a sand filter, followed by the heater. After the heater, we will then have a chlorination system and then this system will feed back into the hot tub via its own wall returns – we would need two of these.
The reason that we would not use the jets to return on this setup is that when the jets were on full, the force even with a non-return valve would block off the flow of water from the circulation pump due to the pressure. Flow would stop and your heater would then give a flow error and stop working.
By having a totally separate heating and filtration system, the issue of flow on the jets is irrelevant. The dedicated jet pump will take care of this.
What is the downside to this setup?
The downside to this dual setup is the cost. Pool parts are always more expensive from pumps to filters to anything that has swimming pool in the name. So, if this setup was more expensive, why would you do it. There are a couple of reasons that come to mine. Parts supply is one. It is much easier to get hold of pool supplies than it is for hot tubs.
Secondly the added filtration benefits sand filters. They tend to be able to filter dust particles a lot better than their hot tub cartridge counterparts.
Food for thought!
Can I help you with your project or parts supply?
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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