How To Get Rid Of Hot Tub White Water Mold Or Mildew (Fungus)



Many different types of organisms can grow in your hot tub.

Left untreated, this can lead to nasty issues with your water, especially when sanitizers such as chlorine or bromine become overwhelmed.

Hot tub white water mold is one of the more common issues, so let’s talk about what it is, if it’s dangerous, and how to keep it out of your hot tub.

What Is White Water Mold?

Anything with “mold” in the name should concern you.

White water mold is a naturally-occurring fungus that’s always present in water.

Also referred to as biofilm (or slime), it sticks to surfaces in the tub and eventually flakes off. It’s easy to spot, as it looks like shredded tissue paper floating in the water.

If left too long, a layer of pink mold may form on its surface (like the pink mold you get in your shower).

While it’s certainly something that needs to be taken care of, getting rid of it isn’t too difficult, and using proper preventative measures can keep it out of your tub long-term.

Why You Have Mold In Your Hot Tub

White water mold is the result of pollutants in the tub mixing with the natural bacteria in water.

These pollutants usually come from bathers. Body oils, dead skin cells, and personal care products are all triggers for an outbreak.

Normally, the sanitizing chemical in your hot tub keeps these pollutants from mixing, reducing the formation of biofilm. However, an inadequate amount of sanitizer gives the mold a strong chance to flourish.

Additionally, white water mold will almost certainly develop when a hot tub goes long periods between cleanings.

How To Remove White Water Mold In A Hot Tub

Got a problem with white water mold in your tub? Here how you can get rid of it.

Clean Or Replace Your Hot Tub Filter

The filter in your hot tub removes offending particles in the water. The downside is that it’s not self-cleaning, so at some point you’ll have to remove it from its housing and clean your filter the old fashioned way.

You should rinse your cartridge filter every few weeks regardless of if you have a mold problem, but if white water mold creeps in, a simple rinse won’t be good enough.

Instead, you’ll have to deep soak the cartridge for 24 hours using a specially formulated cleaning product.

This cleans the filter’s fibers and destroys any mold caught in its pleats. Make sure to rinse it well so that no flakes are reintroduced to the tub once you put the filter back in it’s housing.

In extreme cases, you may want to consider fully replacing the cartridge. Starting from scratch isn’t always a bad thing, and the cheap cost of replacement cartridges makes it easy on your bank account at the same time.

Hit It With Some Shock Treatment

Shocking the hot tub is usually done weekly, and even more frequently depending on how much use the spa is getting.

This process entails adding a massive dose of sanitizer to the water, effectively killing off all bacteria, viruses and pathogens.

With white water mold, a lot of shock is needed to break down the biofilm. The mold might also be in the pipes and filtration system, so maintaining a level of 20 parts per million of shock over a 72 hour period is vital. 

Test the water 3 times – at the 24, 48, and 72 hour intervals – and top up the shock if it falls below the 20 ppm level.

You May Need To Drain And Refill

If you have a serious white water mold and it looks like the water can’t be salvaged, you should consider doing a tub drain.

This process takes some time and also requires you to shock the water after you’ve refilled the spa. This will help rid the filtration system of any mold that may be hiding in it.

Finally, when refilling the tub and running the jets for the first time, there may be flakes in the plumbing that will be circulated into the tub and caught by the filter, so don’t forget to clean the filter to remove any leftover flakes.

How To Prevent White Water Mold

How can you prevent this naturally-occurring mold from occuring in the first place? We have a few tips for you:

Stay On Top Of Your Chemistry

A clean hot tub starts with neutrally balanced water. Adding the appropriate amount of chemicals to the water keeps it safe for bathing.

You should be testing and adjusting the chemical levels a minimum of once a week, and ramping it up when the tub is under heavier use.

This entails balancing the pH level, total alkalinity, and calcium hardness of the water, as well as chlorine or bromine level for your sanitizer.

If these levels fall out of their ideal range, it can cause a chain reaction, upsetting the delicate balance of water chemistry and leading to issues with the tub.

Clean The Tub Regularly

White water mold doesn’t just show up overnight.

In fact, a lot of tubs have a very low level of it that doesn’t cause any problems because the sanitizer keeps it under control.

But if you lax on keeping the water and the tub clean, mold can quickly get out of hand. This is why it’s so important to commit to weekly maintenance of not only the water chemistry, but cleaning the tub itself. 

Wipe down the walls and floor with a soft sponge or cloth. Ensure nothing is contaminating the surfaces (places like the topside controls or drink holders).

Also, clean the hot tub cover if you use one, as mold loves to attach itself to the underside of covers or thermal blankets. 

Always Shower Before Use

The common theme these preventative measures have is this: keep the tub as clean as possible.

Bathers will always contaminate hot tubs, but you can drastically reduce the number of pollutants by showering before you use your spa.

Things such as body oils, hair, dead skin, makeup, lotions, sunblock, and soap residue can all be removed from your person just by showering beforehand.

A reduced number of pollutants in the tub means you’ll get prolonged life from your sanitizer, and it won’t struggle to keep the water clean.

Too many pollutants will lead to overwhelmed chlorine/bromine, and if it isn’t replenished fast enough it can lead to a mold breakout.

What If It’s Not Hot Tub Mold?

White water mold is pretty distinctive in its look, but there are a few other water issues you might confuse it with:

  • Scum. Hot tub scum gives the water an oily look and feel, and you may notice deposits of it building up at the waterline. Scum comes in lovely shades such as brown, green and aqua. These colors tint the tub due to water issues ranging from high metal content, to ineffective sanitizers or compromised filters.
  • Calcium scaling. Hot tub scale is a condition that leaves a chalky, white residue on the tub’s surfaces. This is due to a high level of calcium in the water, which at some point falls out of solution. At times, the calcium can flake off the surfaces and float in the tub, which can be mistaken for white water mold. Fixing these water issues usually requires draining and full cleaning of the spa.
  • Algae blooms. Algae is brought on by a highly contaminated environment. If the sanitizer is no longer adequate, and enough time passes, algae is sure to form in your hot tub. You can help prevent it by adding an algaecide to your tub every week. If the algae problem is substantial, you should fully drain and scrub the tub to remove it.

Hold The Mold!

No one likes dealing with water issues, and hot tub white water mold is a doozy.

But with proper prevention techniques, and the right level of care, you can keep it from ruining your good times in the tub.

Categories: Hot Tub Care, Hot Tub Problems