Seachem Alkaline Buffer for Aquariums, 600 g, Phosphate-Free pH & KH Support

Seachem Alkaline Buffer is a non-phosphate aquarium buffer made to raise pH and alkalinity, with a buffering range of 7.2 to 8.5.

• 600 g (1.3 lbs) — supplies a substantial quantity for aquarium water conditioning.
• Made for planted aquariums — suited to freshwater setups where phosphate buffers may be a concern.
• Contains no phosphate — avoids adding phosphate through the buffer.
• Raises alkalinity (KH) — adjusts this measure alongside pH.
• Designed to buffer with Acid Buffer — works as part of a two-buffer system.
• For very hard water — provides an option when phosphate buffers may contribute to algae or cloudiness.

Choosing a buffer involves more than selecting a target pH: alkalinity also matters to aquarium water chemistry. Seachem Alkaline Buffer is made for planted aquariums and very hard water, particularly where phosphate-based buffers may be undesirable. Its defined pH range helps aquarists identify whether it suits the water conditions they are working to adjust.

What does Seachem Alkaline Buffer adjust?

It raises pH and alkalinity (KH), buffering aquarium water within the 7.2 to 8.5 range. These are the specific water parameters this product is designed to affect, making it relevant when an aquarium needs both pH adjustment and increased alkalinity. The brand describes the buffer as gentle and safe, and says it enhances the freshwater environment.

• Intended for freshwater aquarium use.
• Designed to address pH and KH together.
• Its stated buffering range is 7.2 to 8.5.

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

Seachem Alkaline Buffer contains no phosphate, and is designed for planted aquariums as well as very hard water. This distinction can matter in setups where phosphate buffers may pose an algae or cloudiness problem. The formulation lets aquarists choose a buffer without phosphate as an ingredient.

• Planted aquarium use is an intended application.
• Very hard water is another stated use case.
• The concern addressed is algae or cloudiness associated with phosphate buffers.

How does it work with Acid Buffer, and what size is it?

Seachem Alkaline Buffer is designed to buffer with Acid Buffer. The product size is 600 g (1.3 lbs), giving the buyer a clear quantity when planning aquarium water care. The package size does not provide a dosing amount or step-by-step method, so this page makes no dosing assumptions.

• Designed for use in combination with Acid Buffer.
• Net product quantity: 600 g (1.3 lbs).
• Its stated purpose is aquarium pH and alkalinity adjustment.

This buffer suits freshwater aquarists, especially those managing planted tanks or very hard water and seeking a phosphate-free way to adjust pH and alkalinity. Its defined pH range, KH-raising function, and intended pairing with Acid Buffer make its role clear.

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