Seachem Alkaline Buffer – Non-Phosphate pH & KH Raiser for Planted Tanks

Raise pH and hardness — without feeding algae.

Soft, acidic water and low KH make pH crash-prone, but phosphate buffers invite algae in a planted tank.

Seachem Alkaline Buffer is a gentle, non-phosphate buffer that raises pH and carbonate hardness (KH) and, paired with Acid Buffer, holds pH between 7.2 and 8.5 — ideal for planted aquariums and soft water.

Seachem Laboratories has formulated aquarium chemistry since 1979 at its Madison, Georgia labs, where in-house chemists design products to work as a coordinated system. Alkaline Buffer reflects that approach: it is deliberately non-phosphate so it can raise KH and pH in a planted tank without fuelling algae, and it is calibrated to work alongside Acid Buffer for precise, repeatable control.

1. Use 1 tsp (6 g) per 80 L (20 gallons) daily until the target pH is reached.
2. Pair with Acid Buffer to hold a precise, stable pH.
3. Set your Alkaline Buffer dose by target KH, then use the ratio chart for Acid Buffer.

Stabilize pH the plant-safe way. Add to cart.

Why Seachem Alkaline Buffer

• Plant-safe chemistry: non-phosphate formula raises pH and KH without feeding algae.
• Stable, adjustable pH: paired with Acid Buffer it holds a precise pH between 7.2 and 8.5.
• Guards against crashes: builds carbonate hardness so soft, low-KH water stops swinging.
• System-engineered: calibrated by Seachem to pair with Acid Buffer via a published ratio chart.

Best For

Planted aquariums and soft or RO/DI water where pH is prone to crashing and a phosphate buffer would encourage algae.

FAQ

How much does one dose raise hardness? 1 teaspoon (6 g) per 80 L / 20 gallons raises alkalinity by about 1 meq/L (2.8 dKH).

How do I hit a specific pH? Use Alkaline Buffer with Acid Buffer following Seachem's ratio chart; set your Alkaline Buffer dose by target KH first, then adjust with Acid Buffer.

Why non-phosphate? Phosphate buffers can fuel algae in planted tanks, so this formula raises pH and KH without adding that food source.

What It Does

Non-phosphate buffer that raises pH and alkalinity (KH) and, with Acid Buffer, buffers between 7.2 and 8.5. Gentle and safe; enhances the freshwater environment. Ideal for planted tanks and soft water.

Directions

To increase pH, use 1 teaspoon (6 g) per 80 L (20 gallons) daily until the desired pH is reached (this dose raises alkalinity by about 1 meq/L / 2.8 dKH). To adjust pH gradually, use with Acid Buffer following Seachem's ratio chart to target a specific pH.

Available Sizes

70 g, 300 g, 600 g, 1.2 kg, 4 kg