AC Infinity pH Meter PRO Kit

A complete set with meter, calibration solutions and storage solution. Replaceable probe with a lithium-glass membrane, IP67 waterproof.

The AC Infinity pH Meter PRO Kit is not just a meter but a full set. Alongside the instrument it includes calibration solutions at pH 4.00, 7.00 and 10.01, a 3M KCl storage solution and a probe guard. Stated accuracy is ± 0.01 pH, and the sensor probe is fully replaceable.

What you need besides a meter, and what most people skip

Almost everyone buys a pH meter without registering that the instrument is the smallest part of the story. A meter without the rest is a meter that stops being right within six months.

Calibration solution is the familiar one: liquid of precisely known acidity that the meter adjusts itself against. This set has three, so you can calibrate in the acidic and the alkaline range.

Two things rarely said about buffer solution. First: it has a limited shelf life, especially once opened. Liquid from a bottle that has been open a year calibrates your meter wrongly, and convincingly. Second: never pour used buffer back into the bottle. Your tip always carries something with it, and that contaminates your whole supply.

KCl storage solution is the part almost everyone skips, and it is why probes die early. The glass membrane only measures while hydrated. Storing it dry makes a probe sluggish and eventually useless.

Storing it in tap water or deionised water looks like a reasonable alternative and is not: pure water is ion-poor and therefore pulls ions out of the membrane. You slowly rinse away the thing that makes the measurement possible. KCl solution has a high ion concentration instead and keeps the membrane in the state it should be in. Which is why that bottle is included here.

Replaceable probe

The sensor probe can be replaced separately, and on a meter in this price bracket that is the most important long-term feature. A probe is a consumable: it ages, slows down, and at some point can no longer be brought onto its calibration value. If the probe comes out, you replace a part. If it does not, you replace the whole instrument.

The IP67 housing covers temporary submersion, which in a grow room full of condensation and splashes is the difference between a meter that lasts years and one that quietly gets damp inside.

Technical Specifications:

• Model: AC-PHM5 (PRO Kit)
• Measures: pH and temperature
• Accuracy: ± 0.01 pH (manufacturer's figure)
• Sensor: replaceable lithium-glass membrane
• Protection rating: IP67, dust- and waterproof
• Dimensions: 4.2 x 3.3 x 17.8 cm
• Kit contents: pH Meter PRO, 3M KCl storage solution, buffers pH 4.00 / 7.00 / 10.01, probe guard

Frequently asked questions

Can I measure soil or coco with this?
No, this meter is for liquid. Measuring in a medium needs a probe built for it.

How long do the supplied solutions last?
Long enough for a generous start. Buffer is a consumable: keep the bottle open briefly, never pour back, and replace it once it has stood open a long time.

Why three calibration solutions?
7.00 is your zero point. 4.00 is the second point for the acidic range you grow in. 10.01 is there for anyone measuring in the alkaline range: for most growers it stays unused.

Does it measure the alkalinity of my water?
No. Alkalinity is water's buffering capacity and is determined by titration, not with an electrode. This meter measures acidity itself.

When do I replace the probe?
When it can no longer be brought onto its calibration value, when the reading keeps creeping, or when two measurements moments apart differ noticeably.