How Many Pumps Do You Need for Your DIY Hot Tub?

If you’re building a DIY hot tub, figuring out how many pumps you’ll need is essential for ensuring efficient water flow and a great hot tub experience.

Before we start, this article is meant for DIY builds. For those of you who are buying a hot tub off the shelf, that decision has already been made for you by the manufacturers. 

Let’s dive into the details.

You can also find me on my socials;

Types of Pumps

There are a few types of pumps to consider for your DIY hot tub:

1. Jet Pump: High-powered pumps that operate your jets.
2. Circulation Pump: Responsible for water circulation and filtration.

These come in single speed and dual-speed variants. Dual-speed pumps are more common in DIY builds and setups with a single pump because they offer low speed for circulation and high speed for the jets. 

How Many Pumps for the Jets?

DIY hot tubs generally have fewer jets than factory-made plastic shell tubs. As a rule of thumb, a single hot tub jet pump can handle up to 16 jets, depending on the distance and layout of your plumbing. The further the jets are from the pump or the more complex your plumbing, the more friction there is in the system, which reduces flow.

For a basic setup (with 16 jets and an electric heater), a single two-speed pump can suffice. In low speed, it will handle filtration and heating, while in high speed, it will power your jets. This setup is simple but less popular now, as more DIY builds are going for alternative heating sources like gas or solar.

Flow Rate and Plumbing Friction

A key challenge when using alternative heating methods is maintaining proper flow rate. Every bend, T-joint, gate, or ball valve you add to your plumbing increases friction, reducing the flow rate. If your system can’t deliver enough gallons per minute (GPM) to your jets, you’ll lose power and effectiveness.

Your system is only as good as its weakest link. For example, if you have a high-powered pump but a restrictive sand filter, your flow may be limited to 80 GPM. Since each jet typically needs around 10 GPM, you wouldn’t have enough flow to power all 16 jets.

The Case for Multiple Pumps

To get around flow limitations, many DIY builders opt for multiple pumps. A good system splits the duties:

• A dedicated jet pump for your jets
• A smaller circulation pump for heating and filtration

By separating the systems, you get maximum power to your jets, and a smaller, more efficient pump can handle circulation tasks, saving on energy costs.

Adding More Jets

If you want to install more than 16 jets, you’ll need an additional jet pump. For example, with 32 jets, you’d need two jet pumps. Add another pump for every 15-16 jets to maintain the flow and power of your spa.

Water Features

If you’re planning to include water features like waterfalls or water blades, I recommend using a separate pump for each feature. Not only does this allow you to size the pump appropriately, but it also gives you independent control over the feature. This is particularly helpful if you have a hot tub cover—you can turn off the waterfall without affecting your jets or circulation.

Conclusion

Here’s a quick breakdown of pump requirements:

• 1 jet pump per 16 jets
• 1 separate circulation pump for filtration and heating
• 1 separate pump per water feature (e.g., waterfall, water blade)

While adding multiple pumps might seem like a higher upfront cost, it gives you far more independence in operating your hot tub. Plus, your circulation and jets will run smoothly without interruptions, giving you the ultimate hot tub experience!

 

You can check out the entire range of pumps, water features and other hot tub parts on my website here. 

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