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Why Does My Hot Tub Smell?

Published by Brooke Sardella on 11/30/2022

Why Does My Hot Tub Smell?

Don’t be embarrassed, unpleasant spa hot tub smells are very common, but it is a sign that bacteria are hiding somewhere in your water or equipment. There are a few different causes of this problem and ways to address the issue:

pH Imbalance

The pH of your water can affect the way your water smells. If it is too low, there will be a sharp and pungent smell. If the pH is high you can smell a musty and stale odor. Check the balance of your pH with test strips for ideal levels between 7.4-7.6.


Regardless of what type of sanitizer you use, whether it is bromine, chlorine, or biguanide, check that their levels are high enough to kill bacteria in your water.

It is important to check these levels and shock the water, especially after heavy use. After shocking, make sure to keep your cover open to allow the spa to breathe.


Over time, old spa covers can begin to trap water, which, in turn, grows bacteria that can start to smell. Remove your cover and inspect it for tears or trapped water. You can attempt to repair the cover and dry it out, but your best bet would be to invest in a new cover or go with a hot tub that has a cover featuring a non-porous material.

This is one of the main reasons we sell Strong Spas. Strong Spas have a strong solid cover unlike other hot tub models that is incredibly durable and does not trap water like porous materials do.


Just like your cover, filters don't last forever! They will build up an excess of body oils, minerals, and dirt over time which will allow mold and bacteria to pass by untrapped. It is a good idea to replace your filter cartridge annually and is a super easy fix!


Your hot tub pipes can also become filled with bacteria and biofilm, which can cause the water to smell bad. This can happen if the spa has been neglected for some time or is not properly closed. You can flush the pipes with a cleansing product such as Bio Ouster to remove the biofilm and build-up. We recommend doing this twice per year.


We save draining for last because it is a temporary solution if the problems above are not addressed, the new water you add will just become smelly again! Some hot tub owners drain their tubs every 90 days.

To remedy these issues, you can find the balancing chemicals and supplies here, so you can get your spa back to its relaxing state!