Does your hot tub water seem to go through way more chemicals than normal? Is the water foamy? If so then you may have an issue with biofilm buildup. Today we will look at how biofilm affects your hot tub, and how you can treat it. But first, what is biofilm anyway?

What Is Biofilm?

Biofilm is defined as "any group of bacteria and other micro-organisms that stick themselves to a surface which is in regular contact with water". It is a relatively common problem in hot tubs that causes increased chemical use and issues with water quality.

Biofilm builds up in the plumbing of hot tubs; attaching itself to the surface of the plumbing and cover itself in a protective layer of slime that is resistant to sanitizers like chlorine or bromine.

The plumbing and filtration system in hot tubs provide an ideal environment for biofilms to grow. While it can form naturally under most condition, biofilm thrives in dark, warm (>90°F), water-rich environments. Add in all of the organic material that humans introduce into the water such as lotions, soaps, antiperspirants, and sweat and you’ve got a perfect environment for biofilms to grow. Because of this, even relatively new hot tub (less than a year old) can experience problems with biofilm.

How Does Biofilm Affect Your Hot Tub?

When added to the water, sanitizers will get to work killing bacteria that are present in the water. Whenever a sanitizer comes in contact with bacteria, it kills it. In the process, the sanitizer also changes; becoming ineffective at killing other bacteria.

Biofilm is essentially a sponge for hot tub sanitizers like bromine and chlorine. In a hot tub with a significant biofilm buildup, most of the sanitizer that is added to the water will get "used up" killing the sanitizer-resistant slime layer surrounding the biofilm; leaving the biofilm itself relatively undamaged. Once all of the sanitizer has been spent, the biofilm can then regrow its protective layer. Other bacteria still present in the water can also then begin to multiply.

This buildup of bacteria can cause a wide range of water quality and safety issues; most commonly foamy water, cloudy water and a visible oily ring at the waterline of the hot tub.

To prevent these issues requires adding more sanitizer and balancing chemicals to the water, greatly increasing your chemical costs. Adding more chemicals can also lead to water comfort issues that force you to drain and refill the hot tub water more quickly.

How Do You Remove Biofilm?

To remove biofilm in your plumbing you will need to add a pipe cleaning product, typically right before draining. The cleaner is added with the jets running for a few cycles to allow it to properly circulate through the plumbing system. The hot tub is then drained and re-filled with fresh water. Your hot tub's filters should also be cleaned using a specialized hot tub filter cleaner.

How Do You Prevent Biofilm From Coming Back?

Once you’ve removed the biofilm from your hot tub you will want to keep it out. Enzyme based products like Natural Chemistry’s Spa Perfect or Eco One’s Spa Monthly can be added weekly or monthly to break down oils and other contaminants that build up to form biofilm.

These products use natural enzymes to break down the protective slime layer that covers the biofilm; slowing the formation of biofilm and allowing your sanitizer to more effectively kill it. Continue using plumbing cleaners once per year to clean out any remaining biofilm buildup.