Softub Plumbing Flush: What to Use, How Often, and How to Do It

Every hot tub builds an invisible film of body oils, cosmetics, and biofilm inside its plumbing — and a Softub is no exception. If your water clouds quickly after a fresh fill, the filter clogs fast, or a musty edge keeps coming back no matter how well you sanitize, the pipes are usually the reason. A plumbing flush (purge) run before you drain cleans the system from the inside so the fresh fill actually starts fresh.

For a Softub, use Softub’s own purge product:

• Softcare by Softub Jet Line Cleaner — the plumbing cleaner from Softub’s own Softcare line, built for vinyl-lined spas. Softub is explicit that its warranty expects approved chemicals, and Softcare is the line it approves — so on a Softub, this is the purge we recommend, dosed per its label for your tub’s gallons (140, 220, or ~300 depending on model).
• Pair it with Softcare Instant Filter Cleaner — the purge sends everything it dislodges toward the filter, so the filter gets cleaned (or replaced) as part of the same job.

Purge when you’re about to drain anyway — Softub recommends emptying and refilling 2–3 times a year (the current Softub Water Treatment Guide says 3–4), so most owners land on a purge every water change or every other one. Purge sooner if you’re seeing the symptoms: fast-clouding water, quick-clogging filters, stubborn waterline scum, or recurring musty odor. Always purge before the first fill of a used or long-stored Softub — you have no idea what the previous water left behind.

You may have heard “use SwirlAway every second or third refill” as a Softub rule. That schedule isn’t from Softub — purge frequency is symptom- and usage-driven, and we recommend the products above that we stock and can stand behind.

1. Time it with a drain. Run the purge in the old water, right before your scheduled water change.
2. Remove the filter (spa at operating temperature, per Softub’s filter instructions) so the purge can circulate at full flow. Set it aside for cleaning.
3. Dose the Softcare Jet Line Cleaner per its label for your Softub’s gallons (140, 220, or ~300 depending on model). Hot tubs vary in size and water capacity — always follow the dosage instructions on the product label for your tub’s actual gallon capacity.
4. Run the jets as the label directs. Expect the water to foam and turn ugly — that gunk was inside your plumbing. Wipe heavy deposits from the waterline as they collect.
5. Follow the label’s contact time. The label’s procedure is a same-day purge. Don’t invent an overnight soak — no manufacturer instruction supports it, and prolonged sessions with concentrated cleaner are not something Softub’s vinyl warranty contemplates.
6. Unplug the Hydromate and drain completely — siphon or submersible utility pump, keeping the pump’s suction off the vinyl.
7. Wipe down the liner with a soft cloth and rinse away residue. Clean the filter with Softcare Instant Filter Cleaner (or install a fresh OEM Softub filter if it’s due — Softub says replace at least yearly).
8. Refill, rebalance, and restart the sanitizer following our Softub Softcare water care guide.