Cold plunges started showing up on my route about three years ago, and almost none of them came with a plan for the water. A plunge is 100 to 200 gallons that three people get into after a workout, held at a temperature where chlorine works slowly and biofilm doesn't care. That combination goes bad quietly — the water still looks clear right up until it isn't.
The same thing is true of every vessel in this pillar. A float tank holds so much dissolved salt that the test kit you'd use on a pool gives you numbers that mean nothing. A therapy pool runs warm enough to drive chloramines into the air over people with compromised lungs. None of these are exotic problems, but none of them are pool problems either.
This pillar covers what actually keeps wellness water clean — starting with the cold plunge, because that's the one most likely to be sitting in a backyard or a gym corner right now with nobody testing it.
Full pillar content coming soon. Browse the guides below to start learning.