How to Fill a Hot Tub


Hot tub start up begins with properly filling your hot tub. Filling a hot tub for the first time is exciting and following these simple best practices will make the rest of your spa start up go smoothly.

Follow along with Maddiy, one of Master Spas' TV Hosts, as she guides you through how to fill a hot tub including the importance of checking spa pump fittings, attaching a pre-filter to your garden hose and adding a sequestering agent, as well as how to purge air from hot tub plumbing.

While your hot tub is filling, you may want to watch our "Chemicals for Hot Tub Start Up" video to familiarize yourself with the next step in the process, adding chemicals to your spa for the first time. Hang in there. By following the steps outlined in these two videos, you'll be relaxing in your new hot tub or swim spa in no time.

Steps to Fill Your Hot Tub

In this episode, we're gonna learn how to fill up our Master Spas hot tub.

Here are the things you'll want to have handy to make this go as smooth as possible:

  • Phillips-head screwdriver
  • Garden hose with pre-filter
  • A Sequestering agent to help with initial water treatment

If you're a new owner, filling up your hot tub for the first time, there's a few things you want to make sure are done before adding water. Make sure your hot tub is in its final resting area it's nearly impossible to move once there's water in it. Next, we need to remove the front cabinet section this is the side where the control panel is. Make sure the pump connections are tightened and secure these can come loose during transportation or by the electrician trying to make their connection in the spa pack. We even suggest keeping the front cabinet section off until your hot tub is filled up and running, as long as that's the same day. Removing this cabinet section is easy. Once that prep work is done you're ready to fill up your Master Spa.

First grab your garden hose and pre-filter. A pre-filter is really handy as it removes suspended solids as well as heavy metals found in your source water. Contact your local Master Spas dealer if you need one. We strongly suggest using this as it helps treat your spa water properly and faster.

Next, go ahead and remove the filter closest to the control panel. You want to have water flowing directly through this fitting. This will force air out of the pump and plumbing line which includes the heater and it will help avoid an airlock situation when you start up your hot tub. Just keep an eye out to make sure no other items like leaves make their way down this fitting as they could get stuck in the plumbing pump or even the heater. If you have a filter area that looks like this just go ahead and do what's shown.

Now we're ready to turn the water on. Get back to the hot tub and make sure the hose has stayed in place. Once the water level has filled the footwell you should add the sequestering agent to further combat suspended minerals in the water. Just check out the back of the bottle to see how much you need to add. It's best to give this about 30 minutes to filter through your spa once it's running before adding any other chemicals.

So now it's the waiting game. How fast your hot tub fills up depends on the size of your Master Spa and the water pressure at your house. If you do walk away from the hot tub while it's filling it's a good idea to set a timer as you may forget about it otherwise. You'll want to add enough water to get it to the minimum safe water level. This is really the ideal level as the water level will rise once people start getting in the hot tub. It can be slightly higher than this but should never be lower.

Once you're there go ahead and turn off the garden hose, remove it and replace your filter. If the licensed electrician has already connected your hot tub, turn the breaker on. Once power is initiated to your hot tub it will go through a priming mode. The purpose of the priming mode is to manually activate each spa pump prior to the automatic heat cycle being started. Typically cycling each pump a few times will prime or purge any air from that pumps plumbing. The automatic heat cycle will begin four to five minutes after the priming mode starts. Once this is done we need to check to make sure the pump connections are tight. You'll know they're tight if no water is dripping from them. We can now put the cabinet panel back on. That's it, your hot tub is now full and ready for the next steps.

For European countries, please refer to this Water Chemistry Guide for appropriate chemical levels per BS EN 17125:2018.