Sirona Spa Down | Spa pH & Alkalinity Decreaser

• 1 x Sirona Spa Down (2.5 lb container, granular)

• Lowers high pH — brings alkaline water back into the safe 7.2–7.8 range
• Dual action — reduces both pH and total alkalinity in one product
• Prevents scale and cloudiness — stops the buildup, haze, and discoloration high pH causes
• Protects equipment — guards your heater, plumbing, and surfaces from scale and corrosion
• Keeps sanitizer effective — chlorine and bromine work far better at proper pH
• Fast-dissolving granular — easy to apply and quick to act

The active ingredient, sodium bisulfate, is a dry acid. When it dissolves it releases hydrogen ions that neutralize excess alkalinity, lowering both the pH and the total alkalinity of the water. The target for a spa is a pH of 7.2–7.8 — the range where water is clear, non-scaling, comfortable, and where your sanitizer performs at its best.

It's the mirror image of an alkalinity increaser: where Alkalinity Up (sodium bicarbonate) raises alkalinity and pH, Spa Down (sodium bisulfate) lowers them. Because pH naturally creeps upward in a working spa, this is the balancer you'll typically reach for most often to keep things in range.

Pro Tip: Broadcast it with the circulation running, never into still water. Sodium bisulfate is a concentrated dry acid, and a pile of it sitting on the acrylic shell can etch or bleach a spot. Spreading it across moving water lets it dissolve and disperse instantly, protecting the surface while it works.

Never mix different products together in the same container. Add this product directly to the spa water with the circulation system running. Use when pH rises above 7.8, aiming for a target of 7.2–7.8. Always follow the package label for exact dosing.

1. Test the water to confirm pH is above 7.8.
2. With the circulation running, add 1/4 oz (1 1/2 tsp) per 500 gallons of spa water, broadcasting it over the surface.
3. Retest after about 3 hours. If pH is still above range, repeat the treatment until it sits between 7.2 and 7.8.

Pro Tip: Make pH and alkalinity adjustments before you shock, not after. Your sanitizer and shock work best in the balanced range, so getting pH right first means the chlorine or bromine you add next is far more effective — and you avoid wasting product fighting out-of-range water.

• Brand: Sirona (Sirona Spa Care)
• Part Number: 82104
• Product Type: pH & total alkalinity decreaser (balancer)
• Form: Granular (fast-dissolving)
• Net Weight: 2.5 lb
• Active Ingredient: Sodium bisulfate (95%)
• Function: Lowers pH and total alkalinity
• Use When: pH rises above 7.8
• Target Level: pH 7.2–7.8
• Dosage: 1/4 oz (1 1/2 tsp) per 500 gallons
• Retest: Circulate, then retest after ~3 hours and repeat if needed
• Benefits: Prevents scale, cloudiness, and discoloration; protects equipment; keeps sanitizer effective
• Compatible Sanitizers: Chlorine, bromine, salt, mineral, and biguanide
• Application Note: Concentrated dry acid — broadcast over moving water; never mix with other products in the same container
• Shipping: Ground shipping only (ships via UPS Ground; classified as a regulated dry-acid product)

Sirona Spa Down is compatible with all sanitizer systems — chlorine, bromine, salt, mineral, and biguanide. As a balancer, it's part of the foundation you maintain alongside your sanitizer, regardless of how you sanitize.

It's the counterpart to Sirona Alkalinity Up (which raises pH and alkalinity when they run low) and works alongside a calcium increaser and Sirona test strips. Balance total alkalinity and pH before adding sanitizing and shock products, and before you rely on a clarifier. Never mix it with other chemicals in the same container — add it directly to the spa water.