Custom Built Spas
Call Today: (860) 571-8440

Hot tub Systems Made Simple

Mar 28, 2016 | Building or Buying a Hot Tub

Whether you are considering buying a new hot tub, spa or swim-spa, or maybe the idea of building one of your own using the information I’ve been providing my customers for years, really intrigues you. Either way, there are a number of things about these units and hot tub systems that are important for you to understand so that you can make the best buying decision.

Hot tubs and spas regardless of size, all have the same three basic systems required for their normal operation. These basic systems include the water jet system, heating system and filtration system. From there other systems can also be incorporated into a hot tub. The next two are the most common systems you’ll find with almost all hot tubs and spas, they are air systems and the lighting systems.

On the more expensive spas and hot tubs you’re likely to find upgrades such as sound systems, video systems, waterfall systems and maybe even automatic chemical treatment systems.

The Jet System:

The Jet System is one of the primary hot tub systems in a spa or hot tub. There are literally dozens of different jet styles and performance levels. Don’t ever be fooled with claims that boast “our hot tub has more jets than” … a competitor’s hot tub therefore it’s better. This couldn’t further from the truth. It’s not just about quantity of jets, it’s about jet performance. Fifty smaller jets with low flow will never feel or perform better than say 16-20 jets with a higher flow rate and better water broadcast.

Over the years I’ve advocated two to three high flow large broadcast jets per designated seating position. I’ve never once received a complaint from a customer as to the feel and performance of this typical set up.

Don’t fall prey to the boasts from sales people that their hot tub systems has more HP (horse power) which makes our units better than our competitor’s units. HP is rated several ways and what you’re told and think you’re getting is rarely what your really get. The ratings are “Peak HP”, “Breaking HP” and “Running HP”. Peak and Breaking HP are what I call “BS” HP. It’s true or a running HP rating is what you want to see. A rating of 5HP Peak may only translate to around 2 to 2-1/2 true or running HP. There has been much controversy over this type of rating system over the years but it doesn’t look like it will be changed anytime soon. What you really want to know is what kind of water volume will that pump deliver to each of the jets and at what pressure.

Here’s an example: When we set up a spa with our jets, we know each jet gives the best performance at a flow rate of 10gpm, (gallons per minute), at a water pressure of 12psi, (pounds per square inch). So if you install 16 jets, you want a pump with an output rating of a least 160gpm to 180gpm. Some flow rate is always lost in the plumbing system do to the friction of the water passing through the delivery lines. There are other factors that come into play for a jet system as well, but I just want you to understand the basics.

The Heating System:

The majority of the portable spas built today use electric heaters for water heating. Primarily because they are economical, compact and relatively trouble free and for the most part, easy to service. In most cases the hot tub may only have a water volume of about 350 gallons to around 550 gallons, easily handled with today’s electric spa heaters. Electric heaters can have an output rating of anywhere from 1.5KW to 5.5KW and draw upwards of 22amps to 24amps. A large spa or hot tub used in a cold climate area could even have an 11KW heat unit. In well-insulated hot tub systems with around a 400-gallon water volume, depending where you live and your electric rate, expect your electric bill increase by an average of about $30 to $40 a month, depending on how much you use the spa or hot tub.

Gas heat can also be used for heating spas and hot tubs, either natural gas or propane. If your hot tub has a water volume upwards of 750 gallons or more, you live in a colder climate area and gas is available to you, you might want to consider gas heating. Once again there are a number of other factors that come into play when making the choice of heating with gas. (contact me and I’ll go into greater detail on this).

Filtration Systems:

This has been a pet peeve of mine for years. So many manufacturers outfit their spas and hot tubs with minimal systems. As soon as there is a higher than normal bather load the water begins to get murky. The filter system isn’t able to keep up. Even though there may be enough sanitizer in the water, it’s not being circulated or mixed with the water well enough.

I’m going to take some heat for this one but when I see a spa or hot tub that boasts a 24/7 filtering system, I’m not buying it. These hot tub systems typically have a tiny circ pumps with about 1/15 – 1/16HP with flow rates of around 6 -12 gpm. And the water is being sent through a 15 or 25sq’ filter. (this means it’s a filter with 15 or 25 square feet of filter element surface).

Here’s what I put in my customer’s spa parts packages. At least ½ to ¾ HP pump, with flow rates of 50-75gpm pushing the water through at least 1-1/2” diameter lines and we us 100sq’ filter elements. In over 15 years I’ve never had a customer complain they couldn’t keep their spa and hot tub clean due to poor filtration. Is what we do a little overkill? Yes, maybe but do you want sparkling clear water or not? We also used dedicated filter systems that are set up to vastly increase water circulation within the spa or hot tub itself. To me this is an essential for hot tub cleanliness. Nothing marginal with our system, you can see the water circulating when the filter system is running.

Another way portable spas achieve filtration is by using a 2 speed jet pump with a filter set up on the discharge side of the jet pump. The filter has a bypass valve built into it. When the jet pump runs on high speed the flow is high enough to open the filter bypass and allow the water to pass straight through the filter instead of being diverted through it. When the jet pump is run on low speed the bypass prevents water passing through and water gets diverted through the filter element. The flow rate is better in this set up but once again the filter element size is small.

One of the problems with this set up is that the bypass fitting inside the filter has a smaller diameter than the plumbing line size. Because of this you have a certain amount of flow restriction to overcome to get the same jet performance as a system with no bypass restriction. Adding a little more HP is a common way to up the performance again. But larger HP pumps take more electricity to run them. Again, with portable spas it’s always about saving space and maximizing manufacturer profits!

Air Systems:

Most all spas and hot tubs have some type of an air system. In hot tub systems the air system is simply a set up where air is introduced into jet water flow to produce all the bubbling action. Air can be introduced with what are called air controllers, mounted on the spa deck or by an electric air blower. The air blower HP will vary depending how many jets air is being provided to.

Air controllers when opened up allow ambient or outside air to be draw into the water flow when a jet pump is running. This is called scavenged air, which is simply the drawing of air into the water flow because the water flow for the jets creates a low pressure situation in the air controller and air lines. The result is the bubbling you see in the water.

Now, when you really want to create serious bubbling action, an air blower to hot tub systems. An air blower puts positive air pressure on the air lines and forces much more air to mix with the water flow. An air blower can completely change the feel and bubbling action of the water. 99% of my customers opt to use and air blower. You may notice that jets higher up on a spa or hot tub generally get more bubbling action. This is because the lower a jet is on a hot tub wall; the more water weight an air blower needs to overcome to create air flow. For most spas and hot tubs this is normal.

The Lighting System:

Almost all spas and hot tubs have some sort of a light source to add a little ambiance to the unit. These particular hot tub systems can be anything from a single white or clear light to a colored light to a multi-color light changing unit. Some of the fancier spas and hot tubs may also have lighted jets or lighted waterfall fixtures. These days all spa lighting is pretty much 12V LED type or fiber optic lighting. Lighting up grades are generally not that expensive so if want to splurge a little on this system, I say why not.

My hot tub amber light resized  My hot tub purple light resized

My hot tub green light resized  My Hot tub blue light resized

Sound and Video Systems:

These systems in my opinion should never be built into a spa or hot tub for many reasons. The first reason, I go in a hot tub to relax not to watch a video or TV. I can do that in the house. Sound systems; why not just get an inexpensive boom box and set it up near your hot tub, you’ll save a bunch of money.

The whole idea behind these hot tub systems is pretty much to just to get one up on a competitor’s hot tub or spa. It also allows a customer to one up their neighbor who might also have a spa. So are these systems so important you have to have one in you hot tub? I don’t think so. Not only is it expensive to add these systems, they are often troublesome. The worst part is that if you go to sell your spa or hot tub it doesn’t add anything to the resale value.

So to keep this one short I’ll just say, be practical. Sound systems and video systems are more of a sales gimmick than anything else. I would pass on them.


Although I could get in much greater depth on some of these systems, my objective was to give you enough information to make some good decisions on whatever purchase you make. Maybe you might explore building a spa or hot tub? And as always, if you have any questions or concerns, contact me, I’ll be happy to help you out.

Gene Trumbull
Custom Built Spas



Remember, my Mission is to help you, as my customer, build a beautiful hot tub of your own! I can show you how to build Spas, Hot Tubs, Swim Spas, Plunge Pools, Cocktail Pools or Exercise Pools at incredibly affordable prices! Everything you need to know is outlined in my series of easy-to-follow books and videos that cover a simple, step-by-step process that I’ve developed and refined over the years.

I will teach and help you with everything you need to know about building your own spa, hot tub, or swim spa yourself, regardless of what your DIY skill levels are and at a cost, YOU determine YOU can afford. As my customer, I’ll work with you at your own pace until your project is done and comes to life! For over 25 years now I’ve been helping people just like you, build their own hot tubs, spas, and swim spa projects. So, are you’re ready to let me help you build your project? Then what are you waiting for, let’s do this!

Custom Built Spas