Preventing Biofilm Formation in Spas

Now that you’ve flushed your spa once, twice or as many times as it takes to get it all out, how can you prevent biofilm from forming again?

Remember – biofilm forms when bacteria in solution adhere to a surface, divide and cover themselves with a protective layer of slime (mucopolysaccaride).  Learn more at Montana State University’s CBE site.

You could try to completely sterilize your spa and the spa water and keep it sterile; drain the spa and use fresh water every week; use a flush to remove all biofilm once or twice a month and replace the water; OR you can prevent formation of biofilm while killing all swimming bacteria.  Let’s look at each one.

The Hard Way:

Sterilize your spa and water

There is no easy way to sterilize every surface in your spa short of sending it to an industrial sterilization facility that uses high power x- rays.   Even if that was done, the water placed into the spa would have to be sterilized, and you couldn’t use the spa because the second you stepped into the spa the bacteria on your skin would quickly repopulate the spa water and the spa surface.  In my research laboratory, we conduct many experiments under sterile conditions and keep the systems sterile.  The amount of work and equipment in addition to training required to accomplish that is enormous.

Drain the spa and use fresh water every week

This is essentially how commercial spa operators try to keep their spas within health department guidelines.  They often use a measurement called “total dissolved solids” to determine when to dump the water and start fresh.  Depending on the bather load, this could be done twice a week or weekly.  The water is then treated with a sanitizer like chlorine to keep the bacteria count in the water within safe limits.  This approach uses a lot of water, takes a lot of time, and does nothing to address the formation of biofilm in the spa.  With the biofilm present in the spa, any excess bacterial challenge or change in bather load will “tip the balance” of the water and require more frequent water changes.

Use a flush to remove all biofilm once or twice a month and replace the water

As we discussed in my last blog (September 23, 2009), we now have an effective flush system that efficiently remove biofilm from surfaces and keeps it in solution.  When the spa is drained, the biofilm goes out with the water.  With fresh water and sanitizer in the spa, new biofilm will form over time requiring reflushing and fresh water.  Theoretically, the water should last longer between changes than the previous scenario, but with frequent spa use, flushing would have to be done once or twice a month.  The same problems as above make this treatment plan a real problem.

The Easy Way:

Prevent the formation of biofilm and control the number of swimming bacteria

This solution is ideal.  Up until the discovery that certain species of moss prevent the formation of biofilm, this was a just a theoretical possibility.  We know that sanitizers like chlorine and bromine are very effective killers of bacteria that swim.  We now know that these same sanitizers are absorbed by biofilm and fail to kill all the bacteria within the biofilm.

Here’s how we now think this works: Combining the moss with sanitizer solves the problem.  The moss prevents biofilm from forming, allowing the sanitizers to efficiently do their work on planktonic (swimming) bacteria.  The moss also inhibits bacteria from dividing, so there are fewer swimming bacteria to kill.  Combined with the moss’s ability to remove heavy metals from water and stabilize pH, the spa water becomes stable, clean, clear and safe.  See the video on our website for more information about biofilm and moss.

Tags: Biofilm, commercial spa, spa, spa operator

This entry was posted on Monday, October 26th, 2009 at 9:52 am and is filed under Biofilm. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.