The internet is full of conflicting advice. This is ours: the same standard our technicians follow on every San Diego service visit, written plain so you can keep your water right between our visits.
Test 2–3 times a week — more if you plunge daily or have guests over.
Your sanitizer. Low? Add a small scoop of the granules we left you. High? Just wait — leave the cover off for an hour and it drops on its own.
It naturally creeps up under the cover as the water sits. If it reads high, add a small dose of the pH-down we provided. That's it.
Cloudy or musty water means something's off — text us, don't just keep adding chemicals. Guessing usually makes it worse.
The short list that keeps your plunge clean and your equipment alive.
Our tap water runs roughly 216–276 ppm hardness, already above the ideal range for a plunge. That means two things: never add calcium or hardness-up products (you'd make scale worse), and your plunge benefits from a metal & scale sequestrant to keep minerals from staining the shell or clogging the chiller. We dose this on our visits — it's included in your kit if you're on a plan.
Different shells need different care. Here's the rule for each — and what will damage it.
| Material | Clean it with | Never use |
|---|---|---|
| Acrylic Plunge, Sun Home, Chilly Goat |
Warm water + soft cloth, or a mild spa surface cleaner | Acetone, solvents, abrasive pads — they permanently craze and cloud acrylic |
| Stainless steel Renu, some BlueCube |
Chloride-free stainless cleaner, soft cloth, wipe with the grain. Follow the factory's ozone program — go light on chlorine. | Steel wool, chlorine-based cleaners, abrasives — they seed pitting corrosion |
| Rotomolded plastic ORCA, budget tubs |
Mild soap and water | Pouring sanitizer concentrate directly onto the surface |
| Cedar / wood-lined | Damp wipe, let it breathe, tannin-aware care | Harsh sanitizer soaks (wood absorbs them) and pressure washing |
Not sure what your plunge is made of? Some brands (like BlueCube) ship in stainless, carbon fiber, or acrylic. When in doubt, ask us — we'll tell you exactly what's safe for your unit.
Most premium plunges sanitize the same way — and we follow what your tub was built for.
Nearly every quality cold plunge has a built-in ozone or UV system doing continuous, chemical-free sanitation behind the scenes. On top of that, the manufacturer has you add a residual sanitizer that keeps the water and plumbing protected between sessions — and for most brands, that residual is chlorine. We use exactly what your tub was designed for:
| Your plunge | Built-in | What it's built for |
|---|---|---|
| Plunge | Ozone | Chlorine residual (Sirona Replenish — a 15% chlorine product). Supports chlorine or chlorine-free. |
| Chilly Goat | UV | Chlorine granules, held at 1–3 ppm |
| Renu Therapy | Ozone + filter | Ozone does the heavy lifting; optional chlorine-free Sirona Simply kit if you prefer no chlorine |
| Sun Home · AquaVoss · ORCA · others | Varies | We confirm your unit on-site and match it |
A quick word on "Sirona." You'll see the Sirona name on a lot of plunges — but most of what ships (like Plunge's Sirona Replenish) is actually a chlorine product, not the chlorine-free "Simply" line. We stock the right Sirona products for your tub, so you're using the same brand your manufacturer trusts.
Why chlorine for most setups? Cold water reactions run about twice as slow as a hot tub, so you need a sanitizer that leaves a continuous protective residual between sessions — chlorine does, while peroxide, UV, and ozone alone don't (biofilm can quietly grow in the plumbing). For chlorine-free tubs like Renu, the built-in ozone covers that gap. Either way, we keep it matched to your equipment so you don't have to think about it.
Cloudy water that won't clear · a musty or swampy smell · slimy walls · chlorine you can't keep up no matter what you add · anything that just feels "off." That's a service call, not a chemistry experiment. The longer biofilm sits, the bigger the job — catch it early. Text or call (619) 289-9282.
Our maintenance plans keep your water dialed in year-round — testing, balancing, filters, deep cleans, and the right chemistry delivered to your door. You just plunge.
This guide reflects The Cold Standard's general service practices for residential and light-commercial cold plunges in the San Diego area. Specific dosing depends on your water volume, usage, equipment, and source water — your technician sets the exact amounts for your unit. Commercial and public facilities carry additional regulatory requirements; see our Compliance page. Always follow the safety directions on every product label.