Seachem Aquarium pH Buffer, 600 g Non-Phosphate Formula for Planted Tanks

Seachem Acid Buffer is a 600 g non-phosphate aquarium buffer for lowering pH, designed for planted aquariums and very hard water.

• No phosphate — a buffer option when phosphate buffers may raise algae or cloudiness concerns.
• Adjusts pH to 5.0–8.0 — offers a stated range for aquarium pH adjustment.
• Used with Alkaline Buffer, it buffers between pH 6.0 and 8.0 — supports a combined buffering system.
• Converts carbonate alkalinity (KH) into available CO2 as it lowers pH — links pH adjustment with available carbon dioxide.
• Made for planted aquariums and very hard water — addresses settings where phosphate buffers may be a concern.

Seachem Acid Buffer is for aquarium keepers who want to lower pH without adding phosphate through the buffer. It is designed for planted aquariums and very hard water, where phosphate buffers may contribute to algae or cloudiness concerns. Its role is specific: it provides an acid source, and it can be paired with Seachem Alkaline Buffer to create a buffering system.

What does Seachem Acid Buffer do to aquarium water?

It lowers pH and, as pH falls, converts carbonate alkalinity (KH) into available CO2. The product adjusts pH within the 5.0–8.0 range; when paired with Alkaline Buffer, the two buffers are designed to buffer between 6.0 and 8.0. This makes the pairing relevant when both pH adjustment and buffering are part of the aquarium’s water-management approach.

• Its stated mechanism connects a reduction in pH with the conversion of KH.
• The available CO2 is produced through that KH conversion as the buffer lowers pH.

Why choose a non-phosphate buffer for a planted aquarium?

Seachem Acid Buffer contains no phosphate, making it an option for aquariums where adding phosphate is a concern. The product is intended for planted aquariums and very hard water because phosphate buffers may pose algae or cloudiness problems in those settings. The formulation is a straight acid source rather than a phosphate-based buffering system.

• Choose the Acid Buffer and Alkaline Buffer pairing when avoiding additional phosphates matters.
• The two products are designed to be used together for buffering in the 6.0–8.0 pH range.

How is Acid Buffer different from Acid Regulator?

Acid Buffer is a straight acid source, while Acid Regulator uses a phosphate-based buffering system. Acid Regulator has a greater ability to maintain a constant pH; a straight acid source such as Acid Buffer can have slight pH drift. This distinction helps aquarium keepers choose based on whether avoiding additional phosphate or maintaining a more constant pH is the priority.

• Acid Buffer is the phosphate-free choice between these two systems.
• Acid Regulator is the option with greater pH-maintenance ability, but it is phosphate-based.

Seachem Acid Buffer suits aquarium keepers managing planted aquariums or very hard water who want a non-phosphate acid source and understand its role in a paired buffering system. It is a straight acid source that can have slight pH drift, and its use with Alkaline Buffer provides the stated buffering range of 6.0–8.0.

Read our guide: A beginner’s aquarium set-up checklist: from bowl to tank