Maintaining a spa pool is quite different from maintaining a swimming pool. Even a small private spa requires as much disinfectant as an average-sized pool — heat, aeration and bather load all deplete sanitiser rapidly. Getting the chemistry right from the start makes everything else much easier to manage.
Know your spa's volume
If you are unsure, check with your spa supplier. Most private spas hold between 1000 and 5000 litres. All chemical dosing is calculated per 1000L, so this number matters for every step below.
Balance total alkalinity
Alkalinity is the foundation of water balance and should be addressed before adjusting pH. Target range is 125-175 ppm. Always run the filter pump when adding chemicals — do not run the air blower or venturi.
To raise by 10 ppm
Add 17g of sodium bicarbonate per 1000L
To lower by 10 ppm
Add 20ml hydrochloric acid or 24g dry acid per 1000L
Adjust pH
Once alkalinity is in range, check and adjust pH. Keep it between 7.0 and 7.8 — below 7.0 causes corrosion, above 7.8 reduces disinfectant effectiveness. Use the same acids listed in Step 2 to lower pH, or sodium carbonate to raise it.
Disinfect the water
Option 1
Spa Sanitiser Plus
Initial dose: 50g per 1000L
Daily maintenance: 12g per 1000L
Option 2
Bromine
Keep 4-6 tablets in a floating dispenser at all times
Note: Spa Sanitiser Plus is preferable to liquid chlorine, which degrades over time. Calcium hypochlorite is not recommended as it causes scaling.
Shock weekly
Perform a shock dose at least once a week or after any period of heavy use. Shock oxidises the organic waste that accumulates with use and reactivates the sanitiser.
Chlorine and bromine free alternative
The Aquaspa System
If you would prefer to avoid chlorine and bromine entirely, the Aquaspa range by Lo-Chlor uses PHMB — a hospital-grade antimicrobial with no fumes and a simple 3-step weekly routine.
View the Aquaspa rangeSafe Usage Guidelines
Keep water temperature at 35-37°C
Do not exceed 40°C. Higher temperatures increase health risks and accelerate sanitiser depletion.
Limit sessions to 20 minutes at maximum temperatures
Prolonged heat exposure causes heat stress. Take breaks and hydrate regularly.
Avoid spa use if pregnant, or with a heart condition or recent surgery
Consult your doctor before using a spa if you have any underlying health conditions.
Ongoing Maintenance
Clean the filter at least fortnightly
Or as per the manufacturer's instructions. A clogged filter cannot sanitise effectively regardless of chemical levels.
Drain and refill every 3 months
More frequently with heavy use. No chemical routine can compensate for water that has reached its dissolved solids limit — a water change is the only reset.
