Gunk!! – Your Hot Tub's Dirty Little Secret

A Healthy Hot Tub Starts With Clean & Drain Purge

Much like your body's overall state of physical health, your hot tub's cleanliness has much to do with things you can't see. Uniquely, your hot tub water's appearance and the visible surfaces of your tub are only part of the equation.

In fact, you may see clear water and clean surfaces in your tub, which are good things!

However, the state of your spa's PLUMBING could be another story.

Over time, even the most well-maintained tubs will end up with a buildup of organic debris.

Notably, this debris is known in the spa industry as biofilm.


Definition of the "gunk" in your spa plumbing lines – a thin, slimy film of bacteria that adheres to a surface. Sounds pretty GROSS huh?!

To be exact, it's a gradual buildup of organic and inorganic material. These include bodily oils, lotions, bacteria, water mold, minerals and even dirt.

Water's Choice Hot tub purge

These contaminants accumulate on the inner surfaces of the plumbing lines and multiply over time.

Furthermore, this "gunk" can eventually lead to the necessity to use a greater amount of sanitizer.

You'll also struggle with cloudy water, waterline scum lines/deposits, and foul smells that linger no matter how much or how often you shock the tub.

The good news is that Waters Choice enzymes help immensely in avoiding the issues and you don't have to shock your hot tub.

4 Stages

This "gunk" begins and progresses over four stages: attachment, colonization, growth and distribution. In the first stage of "attachment", this debris simply begins to adhere to surfaces.

Attaching happens beyond the reach of your normal leaning routine, such as the inner wall of your hot tub's plumbing.

In the next stage, "colonization", it accumulates in the same spot(s) where there is already some attachment.

As a colony accumulates it begins to grow thicker and starts protecting itself from the effect of sanitizers.

Correspondingly, it's at this stage we see growth in their little colonies.

During the 3rd stage of "growth", this "gunk" begins to be shielded as it becomes thicker and more resistant to oxidizing chemicals.

Then once the colony has reached a large enough size, the bacteria and debris present move to the "distribution" stage. At this point, the "gunk" is multiplied and spread to other area/surfaces.

Additionally, once these 4 stages have happened, you've reached "critical mass" in the fight to keep your tub clean. **As mentioned previously you may begin to have unpleasant symptoms that aren't easily or quickly cured.

Here's a quick video of what it looks like immediately after using Waters Choice Clean & Drain purge. We think it's pretty neat to see the actual process and how it works. Thank you to our customer who sent this to us.

What to Do

Here's a suggestion about what you can do and more importantly what you can do to PREVENT "gunk" from progressing through its stages and causing problems.

Perform a regular flush of your spa with a high quality purge product such as Waters Choice Clean & Drain.

For typical residential hot tubs, one, 1 oz tube of Waters Choice Clean & Drain should be added to the water to dislodge "gunk" from the hot tub.

Another key point is to be sure to remove your tub's filter cartridges (filters) before adding the Clean & Drain product.

Make sure the jets are running as the whole point is to get the gunk loose and free-floating in the water.

Then, after the tub has run for at least one hour, you'll want to pump all of the water out. Don't forget that while the tub is emptying, wipe down the inside shell with a soft cloth. **Please note: Don't let it dry on the shell or it'll require some elbow grease (hard work) to get the gunk off. To clarify, Clean & Drain is a very powerful and effective purge product.

Flush Your Spa Lines

Water's Choice Hot tub purge

Unless you're using a completely enzyme-based sanitizing system like Waters Choice, you'll want to repeat this flush every 3-4 months when changing water.

It's also important to realize that if you're using Waters Choice Enzymes, you'll only need to perform this flush of your spa plumbing lines approximately one time per year.

Rest assured, you won't be sharing your relaxing soak in the hot tub with anything else hiding in your spa's plumbing.