Can I add a Hot Tub to an Existing Swimming Pool?

Can I add a Hot Tub to an Existing Swimming Pool? The answer is of course you can.

Can I add a hot tub or jacuzzi to my existing swimming pool? This is a question that many people ask me when they are looking to revamp or modify their backyard setup.

When it comes to adding a Hot Tub or Jacuzzi to your existing swimming pool, there are a number of things you need to consider. In this blog post we will explore everything you need to consider before you embark on such a project.

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How Big is the Hot Tub or Jacuzzi Going to Be?

The first thing we need to look it is size. How big is the Hot Tub or jacuzzi going to be that you will add to your existing pool? This will dictate how many jets you will need to install. Remember, the maximum on a single pump is around 16 jets depending on the exact size of the pump, the head height and the flow rate of each jet.

How deep do you expect the Hot Tub to be? Most of the Hot Tubs that I build have a water depth of 900mm or 35.5″.

Hot Tub In Swimming Pool
Hot Tub In Swimming Pool

How many people to you envisage the seating being for?

Do you want to arrange your jets into clusters or do you want to have them in a row around the middle of the back of the seat? Again, this is something to think about.

Do you want the Hot Tub to overflow into your Pool?

Most customers that want to add a Hot Tub to their Swimming Pool want it to be able to overflow into the pool. Looks great doesn’t it. Waterfall flowing into your pool. Just like you see in the resorts.

This is not a problem and the plumbing to do this just requires that there be a swimming pool return line into the tub section. This will allow the swimming pool return line to fill up the hot tub and then once full, it will overflow naturally into the pool.

Likewise, when people get into the tub, the water displacement that a person or persons cause, approximately 70 litres or 15.5 gallons per person, will also cause this to overflow. Not a problem at all as the return line from the pool will then fill the tub back up.

The problem comes if you want to have the temperature different to that of your pool. Think of it like this. If your cooler pool water is being returned into your hot tub that is heating up, it is going to hamper the heating of the water for sure.

It might never actually get up to temperature! We’ll look at heating in a separate section of this post.

What About Chemicals?

If you want to be compliant with guidance, Hot Tub chemical concentrations are different to Swimming Pool concentrations.

This is due to the usual differences in heat between a hot tub and a pool. Obviously, this is down to personal preferences here but if you are going to be overflowing your

Hot Tub into your pool and then refilling from your pool into your hot tub, keeping the chemicals at the different levels is not really going to be possible.

A potential solution to this is adding a chemical free UV System to your setup. This means you don’t need to worry about chemicals in the pool and the hot tub as the UV light will kill all bacteria.

UV is great as you cannot overdose on it. You don’t need to test the amount that is in the water, you simply select a system that can deal with the volume of water that is going through your pool and hot tub.



Can I Use My Existing Pool Plumbing?

The simple answer to this one is yes and no. You can use your existing filter and your existing pump to be used a circulation pump.

You can also use and you should use, your existing return lines to fill the hot tub and make it overflow (if that is the style you are opting for).

What you can’t do as I explain below, is use your pump to power the jets.

Can I Use My Pool Pump for the Jets?

Unfortunately, not. Pool pumps are designed to move large bodies of water through a filter and return the filtered water back to the pool.

They are not designed to force water under pressure through a jet. Also, generally a pool will have a circulation pump that will be less than 1HP.

A jet pump as a bare minimum will be 2HP. You also have to bear in mind that each jet has its own flow requirements. If you don’t have enough flow into the jet then it will now function correctly.

Therefore, when you are adding a Hot Tub to your existing swimming pool you need to put in a separate plumbing system for your jets.

You don’t need to filter this as the pool filter will do that for you. You should however, have two lower drains going into a single speed jet pump (if you are not heating the hot tub separately and a dual speed pump if you are) and then back out into your hot tub. It is a simple plumbing system that is needed to give you the result you are looking for.