Cleaning your hot tub regularly is a necessary action to not only keep a clean, healthy tub for you but also maintain its well-function. A lot of people use vinegar to clean their hot tub filters whereas muriatic is also commonly used with the same effectiveness. Scroll down for a clear guideline on cleaning hot tub filters with muriatic acid.

This post may have affiliate links, which means I may receive commissions if you choose to purchase through links / provide (at no extra cost to you). As an Amazon Associate, I earn from qualifying purchases. Please read my disclaimer for additional details.

Is muriatic acid good for hot tub cleaning?

To keep the tub healthy to be used, the water in it should be maintained, cleaned, and neutralized.

Compared to many other cleaning substances, muriatic acid is considered to be quite effective. It can be used for multi-purposes like cleaning, disinfecting, or controlling pH in your tub.

But using muriatic acid requires considerable caution because it is very corrosive. Always checking out closely the instructions provided by the manufacturer is necessary. Following is our guide for you to safely clean your hot tub with muriatic acid.

How to clean a hot tub filter with muriatic acid?

how to clean a hot tub filter with muriatic acid

First and foremost, protect yourself by wearing gloves and goggles. You may think it is okay to overlook this step, but you are working directly with the strong acid, not only a small proportion of it in a cleaning product already mixed by a manufacturer.

With the above acknowledgement, you will then have to dilute the acid. The strongest solution ration you will ever want to use is 1:4 of acid and water. But for this specific task, 1:20 is effective enough and more importantly, it remains safer for you.

Fill the bucket with water then add the acid following the above ratio. Always add the acid into the water, not the other way around. Then rinse the filter under a strong stream of water and soak it in the acid liquid.

After a sufficient amount of time, rinse the filter with water again before use. You may also want to neutralize the acid liquid by adding a pH-up product before discharging it.

How long to soak the filter in muriatic acid?

Due to the high pH level or mineral content of the water inside the hot tub, after a long time running, debris can stick to your filter and make it clogged. Over time, if not getting cleaned and maintained properly, your filter cannot function long-term.

Soaking the filter completely in muriatic acid for 12 to 24 hours is effective enough to wash off all the stubborn build-up. But because of the strong corrosive nature of muriatic acid, only do this once every year to prevent the acid from affecting the function of all filter elements.

If you want to clean your hot tub filter after every season, instead of using muriatic acid, it is better to hose it down and then use a normal filter degreaser substance.

How much muriatic acid to use?

You only need a bucket of water and acid mix to completely soak your filter in order to clean it. In case you want to clean not only the filter but the whole hot tub, then how much acid should be used?

The amount of acid is determined based on the current levels of pH and alkalinity in your tub, also the amount of water the tub is holding. Then read the label on the muriatic acid to know exactly how much you will need to add.

If you are in a bit of a rush to calculate all the amount precisely, you can take a bucket of water out of your hot tub, then mix in the acid with a 1:10 ratio, stir well and pour it back into the tub.

Some notices when cleaning hot tub filters with muriatic acid

As we have mentioned earlier, cleaning hot tub filters with muriatic acid should only happen once every year to sustain the long-term function of the filter. More frequent cleanings are better taken with the use of a normal cleaning mix or filter degreaser.

Always wear gloves, goggles, and protective clothes when working with the acid. Avoid splashing and spilling as much as possible and make sure to work in an open, air circulated environment.

There will always be services available from pool companies to professionally clean your hot tub. So, if you are not a DIYer yourself and you are unfamiliar with handling the acid, it is a good idea to ask experts to take on this task for you.

Recently, there have also been pre-mixed solutions with adequate amounts of acid inside with clear instructions on how to dilute. This can be a smart choice for you, too.

Remember to replace your hot tub filter every year


You may think regular cleaning up is a necessary action to maintain the function of your hot tub as well as to save money. But actually, keeping the filter running more than its lifetime will be more likely to increase electricity costs, eventually, damage the tub’s water pump, and of course not being able to effectively clean the water.

It is highly advised to replace the hot tub filter once every 18 months, despite the brand new look to your bare eyes.

It may still look new and functioning finely to you, but looking from a microscope, the filter’s pores may have been worn out or already get clogged with oil sediment and thus not functioning at its maximum.

The particulates can therefore pass through it and go into the pump and eventually damage the pump and its surrounding area.

So, after one and a half years, it is a good time for a new filter for your hot tub. Apart from the purpose to keep the rest of the hot tub in a healthy performance, it is also better for you to use a clean, well-filtered hot tub, isn’t it?

When cleaning or removing the filter, follow instructions from the manufacturer to avoid unwanted damage. Also, pay attention to the type, model, or other details as each manufacturer may provide different filters for different hot tubs.

Be safe with the acid!

Cleaning hot tub filters with muriatic acid is surely effective but should be carried out with caution and clear understanding. We hope this post brought enough insight for you to properly clean the filter and maintain the function of your hot tub!

Leave a Comment