• High-range reference point - pH 9 buffer solution calibrates the upper end of the scale, closer to typical reef and marine pH than a pH 4 or pH 7 solution alone.
• 60 ml bottle - several calibration cycles per bottle.
• Pairs with pH 7 fluid - use both for a proper two-point calibration instead of relying on a single reference.

Suitable for: calibrating any BNC-style pH probe on a reef or marine system, including Aqua Medic's pH Monitor and pH Computer Set.

Not suitable for: drinking, dosing into tank water, or use as a general water conditioner - this is a calibration reference fluid only.

Cap the bottle immediately after use and never pour used calibration fluid back in - contamination is a common reason a probe calibrates cleanly but then drifts within days. Recalibrate on the same four-week cycle recommended for the pH 7 fluid.

As a single-use test consumable, this fluid is not covered by a manufacturer warranty, but your purchase is protected by the consumer guarantees available under Australian Consumer Law. This item ships as a standard small parcel with no special freight handling required.

Why calibrate with pH 9 instead of pH 4?

Freshwater meters are often calibrated with pH 4 and pH 7 because freshwater tanks sit below neutral. Reef and marine tanks typically run between pH 7.8 and 8.5, so a pH 9 reference point brackets that range far better than pH 4 does.

Do I need both the pH 7 and pH 9 fluid?

Yes, for an accurate two-point calibration. A single-point calibration only confirms one spot on the scale; using both fluids lets your probe correct for any slope error across the range it actually reads.

How long does one bottle last?

That depends on how often you calibrate - Aqua Medic recommends roughly every four weeks - and how much fluid you discard per session, but 60 ml comfortably covers several calibrations.