Is Biofilm Lurking in Your Hot Tub?

Unpleasant subject coming up! This post is about biofilm bacteria that can form in the plumbing and equipment of spas and hot tubs. The good news is that biofilm is removable (in most cases) and preventable. But first, we have to know more about the hidden bacteria biofilm

What is Hot Tub BioFilm?

What is Hot Tub BioFilm?

According to the BioFilms: The Hypertextbook

"A biofilm is composed of living, reproducing microorganisms, such as bacteria, that exist as a colony, or community. In other words, biofilms are alive and have a complex social structure that scientists and engineers are still trying to unravel, a structure that both protects them and allows them to grow." Alfred B. Cunningham, John E. Lennox, and Rockford J. Ross

Biofilms are naturally occurring, everywhere. Algae on your hot tub walls is also a biofilm, but we're not talking about algae in the pipes. This is more of a mixture of bacteria with solids, oils and other organic matter.

  • Reduces pipe diameter in acute cases
  • Can harbor harmful bacteria colonies
  • Consumes sanitizer, affects pH and spa balance
  • Causes foaming and water problems

Today's above ground spas have lots of plumbing pipe, running to numerous spa jets all around the shell. Most have well over 100 feet of pipe. The interior surfaces, never getting a wipe down, develop a film of solids that coats the pipes, or finds other areas to attach itself, inside almost every part of the spa that you don't see.

Where Does Hot Tub Biofilm Come From?

Where Does Hot Tub Biofilm Come From?

Biofilm can form in spas that have been sitting unused, either full of water or drained, but still with water in the pipes. Biofilm can also come from active, normal use of your hot tub. Our own dead skin cells, body oils, cosmetics and other organic matter are used as building blocks by biofilm, as they establish colonies in low turbulence areas of your circulation system, and attach to surfaces when the pump shuts off.

Spas that are maintained poorly, such as those with old filter cartridges, or the sanitizer - not enough, inconsistent or incorrect use of (don't use pool tablets!), or water not balanced and not shocked regularly - these practices can also lead to biofilm formation. Also, spas that have high usage, hot tubbin' every night, with many users - can have fast colony formations, if the spa sanitation and filtration is lacking.

Even new spas can come with biofilm from the factory, although most reputable manufacturers sanitize and air dry the piping now after water testing, to ensure that while sitting in storage they are not breeding grounds for bacteria.

Used spas? You may find a low price on a used spa, but if it's been used and abused, or neglected, it could have a big problem with biofilm inside of the pipes and equipment. I hear of this happening all the time.

Testing for Hot Tub Biofilm

It's almost impossible to test for and identify as well. It's nearly microscopic in it's young stages. If you can empty the spa, a Q-tip swabbed inside of a few jets, main drain, the filter body or inside the pump drain plug may turn up some funny colors.

If you can disassemble part of your spa jets, you can inspect inside for any thin layers of oily or slimy substances, usually in a brownish shade. Spas with a scum ring that develops around the water line or behind the spa pillows, may have a biofilm problem.

Removal of Biofilm in Hot Tubs

First, lower the spa pH to 7.2, and lower the spa temperature to an unheated state. "Super Shock" the spa with a 4x normal shock dosage of non-chlorine spa shock. In extreme cases, it may be necessary to shock the spa with even more, to kill the bacteria and weaken the organism.

Use a cleaning product, such as Natural Chemistry's Spa Purge. Just pour in 1 pint and circulate the spa for an hour, and then drain the spa. These products break apart the biofilm from every hidden area.

Give the spa another additional rinse and flush with your garden hose. Spray water into every jet and orifice that the nozzle will fit into. Drain remaining water and refill the hot tub. Balance the chemistry and begin sanitation and filtration. Replace your spa filter cartridge, to be sure that bacteria is not hiding deep in the pleats of the spa filter.

Prevention of Biofilm in Hot Tubs

  • Change the water every 3-6 months based on frequency and number of users
  • Use Spa Purge every time you drain the spa
  • Maintain proper water balance and continual sanitizer level
  • Replace your spa filter cartridge every 12-24 months
  • Shock the spa or hot tub after heavy use, or twice per month
  • If you drain the spa or jetted tub and don't refill immediately, use air to blow the pipes dry

If you maintain your spa well, you'll have nothing to fear - as long as you are using a Spa Purge product regularly to strip the pipes and hidden interior spaces of BioFilm!

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Leslie’s makes every effort to provide accurate recommendations based upon current ANSI/APSP/ICC-5 2011 (R2022) standards, but codes and regulations change, and Leslie’s assumes no liability for any omissions or errors in this article or the outcome of any project. You must always exercise reasonable caution, carefully read the label on all products, follow all product directions, follow any current codes and regulations that may apply, and consult with a licensed professional if in doubt about any procedures. Leslie’s assumes no legal responsibility for your reliance or interpretation of the data contained herein, and makes no representations or warranties of any kind concerning the quality, safety, or suitability of the information, whether express or implied, including, without limitation, any implied warranties of merchantability or fitness for a particular purpose.