pH Decreaser Sodium Bisulphate 1kg | Pool & Spa pH Down
pH creeping too high in your spa or pool? pH Decreaser (Sodium Bisulphate) is the fast, reliable way to bring pH back into the ideal range, protecting your swimmers from irritation, keeping your chlorine effective, and preventing scale buildup on equipment and surfaces.
The 1kg pail is the perfect size for spa owners, small pools, or anyone who wants a top-up supply on hand. When pH rises above 7.6, chlorine loses up to 90% of its effectiveness and water turns cloudy. A quick dose of Sodium Bisulphate brings it right back into range.
Product Specifications
| Active Ingredient | Sodium Bisulphate |
| Size | 1kg |
| Target pH (Pools) | 7.2 - 7.6 |
| Target pH (Spas) | 7.2 - 7.8 |
| Suitable For | All pool and spa types including saltwater |
| Packaging | Resealable moisture-resistant pail |
Key Features
- Sodium Bisulphate Formula. Fast-acting granular pH reducer, the industry standard for lowering pool and spa pH.
- Fast-Acting. pH begins dropping within 30-60 minutes of application.
- Dual-Purpose. Suitable for swimming pools and spa pools of all types.
- Prevents Scale Buildup. Stops calcium deposits forming on pool surfaces and fittings.
- Boosts Chlorine Efficiency. Chlorine works best at correct pH levels, maximising sanitiser value.
Dosing Guide
Spa Pools:
- Add 10g per 1,000L to lower pH by approximately 0.5
- Pre-dissolve in a small bucket of water before adding
- Run jets while dosing for even distribution
- Retest after 30 minutes before re-dosing
Swimming Pools:
- Add 500g per 50,000L to lower pH by approximately 0.5
- Pre-dissolve in a bucket of water before adding to the pool
- Pour near the skimmer or return jet with pump running
- Allow 6 hours of circulation, then retest before adding more
Tip: Always test pH before and after dosing. Target 7.2-7.6 for pools, 7.2-7.8 for spas. Dose gradually, it is easier to add more than to correct an overshoot. Sodium Bisulphate is corrosive, wear gloves when handling.
Available Sizes
- 1kg Pail (this product) - ideal for spas or small top-up doses
- 4kg Pail - most popular for regular pool maintenance
- 10kg Pail - best value for large pools or frequent use
Recommended Accessories
- pH Increaser (Soda Ash) 1kg - use when pH drops too low and needs raising back to 7.2-7.6.
- Alkalinity Increaser 4kg - stabilise Total Alkalinity first to make pH easier to control.
- Crystalline Chlorine 4kg - sanitise at the correct pH for maximum effectiveness.
- 5-in-1 Test Strips - test pH, chlorine, and alkalinity before and after every dose.
Frequently Asked Questions
Q: How quickly does pH Decreaser work?
A: pH begins dropping within 30-60 minutes of application. Allow 6 hours of full circulation before retesting and re-dosing if needed.
Q: Can I add pH Decreaser and chlorine at the same time?
A: No, always adjust pH first, wait 6 hours, then add chlorine. Adding both together reduces the effectiveness of both chemicals.
Q: What if I add too much and pH drops too low?
A: Use pH Increaser (Soda Ash) to bring it back up. Always dose gradually and retest before adding more to avoid overcorrecting.
Q: How long will a 1kg pail last?
A: For a 1,000L spa dosed at 10g to lower pH by 0.5, a 1kg pail provides approximately 100 doses, plenty for a full season of regular adjustments.
Q: Why is my pH always rising?
A: Common causes include saltwater chlorinators, high Total Alkalinity, and aeration from jets or waterfalls. Check your Total Alkalinity first, if it is above 120 ppm, lowering it will help stabilise pH naturally.
Q: Is Sodium Bisulphate safe for all pool types?
A: Yes, safe for concrete, fibreglass, vinyl liner, and tiled pools, and all spa pool types when used as directed.
Pickup and Delivery
Perfect Pools Service Warehouse - 15C Douglas Alexander Parade, Albany, Auckland
Hours: Mon-Fri 9am-4pm | Sat 10am-2pm
NZ-wide delivery available. Charges calculated at checkout.
Questions? Email perfectpoolsnz@gmail.com or visit our contact page.
