Seachem Reef Buffer

Seachem Reef Bufferraises and holds reef pH at 8.3 while also lifting carbonate alkalinity, the two numbers that keep stony corals and coralline algae thriving. Unlike plain sodium bicarbonate, it is a blended carbonate and bicarbonate buffer with a higher pK (about 8.6 in saltwater) that is formulated to overcome the organic acids reef tanks produce, so it cannot accidentally overshoot pH to a dangerous level. Browse our full range of additives and supplements and the rest of the Seachem lineup.

Why Reefers Use It

• Raises pH and alkalinity together.Lifts pH toward 8.3 and adds carbonate alkalinity in one product.
• Reef tuned.The higher pK is built to counter the organic acids that drag reef pH down.
• Will not overshoot.Holds at 8.3 rather than pushing pH dangerously high.
• Blended formula.Carbonate and bicarbonate salts, not just baking soda.

How to Use

Use 5 g (1 level teaspoon) for every 150 litres (about 40 US gallons) to raise pH by roughly 0.1 unit, which also raises alkalinity by about 0.5 meq/L. In an established reef, dosing every few days to twice a week is usually enough to hold your target. Do not let alkalinity climb above 6 meq/L, and never mix Reef Buffer directly with calcium, magnesium, or strontium supplements. Always test pH and alkalinity before and during dosing.

Choose Your Size

Size	Best for
50 g	nano reefs and occasional correction
250 g	a single reef tank, regular maintenance
500 g	larger reefs or frequent dosing
1 kg	big systems and fish rooms

Specifications

Brand	Seachem
Type	Reef pH and alkalinity buffer
Targets	pH 8.3 (will not overshoot)
Alkalinity	Raises alkalinity by about 0.5 meq/L per dose
Composition	Blended carbonate and bicarbonate salts (pK about 8.6)
Form	Powder
Water type	Reef and saltwater only
Dose	5 g (1 tsp) per 150 L (about 40 gal), as needed to hold target
Sizes	50 g, 250 g, 500 g, 1 kg

Recommended Pairings

• Seachem Marine Buffer for fish-only marine tanks that need pH support without the reef-tuned formula.
• pH and alkalinity test kits to track your numbers before and during dosing.
• Calcium, magnesium, and trace supplements to balance the rest of your reef chemistry.
• Saltwater livestock and supplies for the rest of your reef.

FAQ

What is the difference between Reef Buffer and Reef Builder?
Reef Buffer mainly affects pH, raising both pH and alkalinity. Reef Builder mainly affects alkalinity and is used to raise alkalinity without changing pH. Many reefers keep both on hand.

Can I use it in a freshwater or fish-only tank?
It is made for reef and saltwater systems. For a fish-only marine tank, Marine Buffer is a better fit, and for freshwater you should use a freshwater alkaline buffer.

Will it raise my pH too high?
No. Reef Buffer is designed to hold pH at 8.3 and will not overshoot to dangerous levels.

Can I mix it with my calcium or magnesium supplement?
No. Never combine Reef Buffer directly with calcium, magnesium, or strontium additives. Dose them separately and keep alkalinity below 6 meq/L.