How to clean a hot tub
Quick answer
A proper clean is tied to a water change: flush the plumbing with the old water still in, drain, wipe the shell and waterline, clean or replace the filter, then refill and rebalance alkalinity, then pH, then sanitizer. Doing it in that order is what makes a fresh fill stay clean for months instead of clouding in a week.
Wiping the shell of an empty tub is the easy part. The clean that actually matters is the one that reaches the biofilm hiding in the pipes, so this routine starts there and ends with a balanced fill.
The full clean, step by step
- Flush the plumbing first. With the old water still in, add a spa line flush, circulate for the time on the label, and let the jets push out the hidden biofilm. You will often see gunk surface. This is the step a quick clean skips, and the reason fresh water clouds fast when it is skipped.
- Power off and drain. Switch off at the breaker so the heater cannot run dry, then drain through the spigot or, faster, a submersible pump. Send the water away from the foundation.
- Wipe the shell and waterline. A soft cloth and a spa surface cleaner lift the scum ring of body oils that collects at the waterline. Skip household cleaners, which foam the next fill.
- Clean the filter while it is out. Soak the cartridge in a filter cleaner to strip oils a rinse leaves behind, or fit a fresh one. See cleaning the filter.
- Refill through a pre-filter. A hose pre-filter cuts metals and hardness going in, which makes balancing easier.
- Heat and rebalance. Power on, then balance in order: alkalinity into 80 to 120 ppm, pH to 7.2 to 7.8, then sanitizer to target. The dosing calculator sizes each step for your gallons. The full refill walk-through is in drain and refill.
Add in small steps with the pump running, wait, then retest before adding more. Never mix chemicals together, and always follow your product label, which wins over any calculator.
How often to deep-clean
Pair the deep clean with each water change, which for most home tubs lands every three to four months (your exact interval comes from the bather rule). Flush the plumbing every few changes, or any time the water has been neglected or you are clearing a white water mold problem. Between changes, the waterline wipe and a clean filter keep the shell looking after itself.
What helps
A spa line flush for the plumbing and a cartridge cleaner for the filter soak do the heavy lifting.
Get spa plumbing flush Get filter cleaner
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Common questions
Do I have to drain the tub to clean it?
For a real clean, yes. You can wipe the waterline and clean the filter with water in, but the plumbing flush and shell clean that prevent recurring cloudy water and biofilm need the tub drained. Tie the clean to your regular water change so it is one job, not two.
Why flush the pipes before draining?
A plain drain leaves a film of biofilm and old oils in the pipes behind the jets, and that film seeds the next fill. Running a line flush with the old water still in, then circulating it, lifts that gunk out through the jets so the fresh fill starts genuinely clean.
Can I use household cleaners on the shell?
No. Dish soap and general cleaners leave residue that foams the water and can damage the acrylic. Use a spa surface cleaner, or just a soft damp cloth, on the drained shell, and rinse before refilling.