How To Clean A Hot Tub That Has Been Sitting

A hot tub can make for a relaxing environment. But it is not uncommon to come outside and notice that the water is looking pretty questionable. This is often because the water in the tub has been sitting for days or weeks at a time without being properly filtered or sanitized.

Spa water that sits for long periods can grow bacteria and algae. This requires the need to clean the hot tub properly. There are a couple of different ways to do this. Follow this step-by-step guide to get your hot tub looking clean and clear again.

How To Clean A Hot Tub That Has Been Sitting

1)Test the Filtration System

The first thing that you should do is to make sure that your hot tub’s filter and pump are working properly. This can actually save you a lot of cleaning in the end. You might need to add some water to bring it up to the mid-skimmer level, which covers the hot tub’s filter.

Turn on the power and open up your hot tub’s cabinet. Reset any potentially popped GFCI outlets. Check to ensure that all of the valves are properly opened and make sure to check for any leaking water underneath the hot tub.

You can then run the hot tub at different speeds which can work to dislodge any debris or junk that may be laying within. There are even some hot tubs that have two different pumps: a jet pump and a circulation pump. Test them both to make sure that they will work later on.

2)Drain the Hot Tub

The best way to clean a hot tub thoroughly is to drain it. If the water looks sort of hazy but you don’t notice any visible biofilm or algae growth, you can skip ahead to the next step. But if the water sits for a while, there is a good chance that it will look more than a little questionable.

Start by looking for the drainage hose or port. This can differ based on the model; if you have any questions, refer to the user manual for your hot tub. Whichever method you use, the idea is the same: let the water drain out via gravity. If you’re impatient, you can use a submersible pump to get the job done.

Make sure that the hot tub’s power is off before you drain it.

3)Clean the Surfaces

Now that the water has properly drained out of the hot tub, you can focus on cleaning the surfaces. In most cases, you can use a garden hose to spray off all of the surfaces. You should also spray off the skimmer and the spa jets directly as they can build up with gunk and slime.

Be careful not to spray the internal components of the hot tub. This includes the heater, the filter, and the pump. These pieces are not meant to get wet and spraying them with the hose could damage them, sometimes permanently.

When the grime builds up on the surfaces (walls and floor) of the hot tub, you may need to break out the soap and a sponge. The only way to get a thorough clean on all the surfaces is to scrub it down completely. Keep in mind that you won’t have to do this every time if you regularly clean the hot tub.


When you’ve cleaned out all of the gunk and debris from the previously funky water, you need to purge the hot tub. With this step, you’ll need a specialized chemical to remove any potential biofilm that could be lining the inside of the pipes. This chemical will work its way through the plumbing and clean out those tight areas completely.

Whatever product that you use, ensure that you follow the directions to the letter. These are very specific chemicals that are meant to get rid of any leftover debris. Finally, turn on your hot tub’s blower and jet pump. This will work to dislodge bacteria and algae that could be leftover in the pipes.

5)Drain Again

After you have eliminated all of the algae, bacteria, and grime that can build up in a hot tub that has been sitting for a while, you’ll need to drain it once again. Use a rag or hose to get rid of any remaining scum that might be sitting at the top of the spa. As the water drains out, clean just above the waterline.

The goal here is to get rid of any loose bacteria or grime that may be floating in the water. This is the only way to ensure that your hot tub is completely clean. The last thing that you need is to clean out the hot tub completely only to find that there is still some algae and bacteria leftover.


When you’re comfortable with the level of clean in your hot tub, it’s time to refill it once again. After completely filling up the hot tub water levels, you will want to test out the water chemistry. This will tell you whether or not you need to adjust the chemicals to provide proper pH balance, calcium hardness, and alkalinity.

You can also add a bromine booster before shocking the hot tub with a few teaspoons of hot tub shock. Depending on the severity of the grime build-up, you may need to replace the hot tub filter. It is a good idea to replace it every 18 months or after the 12th cleaning, whichever happens first.

Getting Rid of Brown Stains

In the more extreme cases, you may notice that there are brown stains that ring the entire hot tub. Don’t panic; there are things that can be done to get rid of those brown stains. The first is to use baking soda and a damp cloth to scrub away those stains.

Vinegar is also a great household cleaner that can be used to take out a number of tough stains. Mix some water and white vinegar together to get rid of those brown stains or any hard water stains that may be permeating the hot tub. Vinegar is also a great way to deodorize your hot tub, too.

Lastly, you can try any number of hot tub cleaners. There are several that have been designed to not only get tough stains out of your hot tub, but protect the balance of your hot tub’s chemicals as well. Try a few different things out to see which one suits you best.

When to Shock the Hot Tub

Every once in a while, you will need to shock the hot tub. Generally speaking, it is recommended that you do this once a week or so. If you use the hot tub a lot, you’ll want to do it more often than that. You want to shock the water when it looks a little murky or smells funny, but the levels are still good.

You can also shock your hot tub if you haven’t used it in quite some time. Shocking the water is a great way to clean it but it will also kill any bacteria that may be sitting in the water itself.