Buying guide for Best pH meters
Whether you’re testing the acidity of the water in your home or your latest batch of home brew, a pH meter is a helpful tool to have on hand for measuring acidity. A pH meter measures the hydrogen-ion activity of a liquid or surface — in other words, its acidity or alkalinity — using an electrode.
The three common types of pH meters are pen-style meters, handheld meters, and benchtop meters, all of which serve the same purpose but vary in design and sometimes in capability. Pen-style pH meters are compact and convenient but often lack the accuracy of benchtop pH meters. While basic pH meters only measure the acidity of a substance, pricier models may measure qualities like the conductivity or temperature. Nearly all modern pH models have LCDs, but the size of the display and its readability can vary.
Key considerations
A pH meter may be used for brewing beer or wine, fermenting food, making cheese, maintaining swimming pools, checking the acidity of tap water, and numerous scientific applications. Your needs should inform the type of pH meter you select, as some models are more accurate than others.
Design
The design of a pH meter determines how it is used and how portable it is.
Pen-style pH meters are the least expensive and easiest to use. They are slim and small enough to fit in your pocket. The electrode in the tip is used to take measurements. These may be waterproof and can be used with one hand.
Handheld pH meters have a large display and an electrode at the end of an attached cable. This design requires two hands to use, though it is still a highly portable option. Many handheld pH meters are waterproof; some are also shockproof. The computer in a handheld meter is often more capable than that of a pen-style meter.
Benchtop pH meters are by far the most expensive options and are designed for lab work. They are often the most accurate and use a variety of electrodes specific to different types of work. Benchtop pH meters are easy to use and well-suited to a variety of tasks. Some have the ability to track your data as you work.
For measuring solids (like cheese) or soil, a pH meter designed specifically for the job is needed. Surface pH readers are commonly used for food, and soil pH readers are used for measuring the pH of soil.
Accuracy, range, and resolution
Most pH meters have an accuracy of around +/- 0.01 to +/- 0.02. Higher accuracy is always better, but it often comes with a higher price tag. If you are working with cheese, beer, or wine, you will need an accuracy of at least +/- 0.01. Some benchtop models are as accurate as +/- 0.001.
The range of a pH meter should be appropriate for the substance you are measuring. Most meters can measure from pH 0 to +14, while meters with an extended range may be capable of measuring from pH -2 to +20.
The resolution is the amount of information that can be displayed on the screen of a meter. A pH meter with 0.1 resolution will display the pH in tenths.
Temperature correction
The temperature of a substance affects its pH. As a result, temperature correction is often necessary for a pH meter to take consistent measurements. While many entry-level pH meters have no temperature correction, some have manual or automatic temperature correction. Automatic temperature correction is the easiest and most desirable option. Manual temperature correction requires you to input the current temperature of the substance you are measuring.
If you opt for a model without temperature correction, try to measure a particular substance at the same temperature each time for accurate results.
Display size
The display of your pH meter should be large enough to read clearly while you work. Most displays simply show the pH measurement taken most recently, but some show additional data such as temperature, salinity, and conductivity.
Ease of calibration and calibration points
There are two ways to calibrate a pH meter: manually and automatically.
Meters with manual calibration have two knobs you must maneuver to properly calibrate your meter. This takes some skill but may result in a more accurate measurement. Automatic calibration is performed by pressing a button on the meter. Some models offer you the choice of manual or automatic calibration.
Carefully follow the included instructions when calibrating your pH meter. In most cases, it involves placing the electrode in a buffer solution and pressing the automatic calibration button or turning the manual calibration knobs.
The calibration method for pH meters is either one-point, two-point, or three-point calibration. This refers to the number of buffers a pH meter uses to calibrate, with more points resulting in greater accuracy.
Sealed or refillable electrodes
The electrode in a pH meter is filled with a solution that will dry out over time. This means the electrode must either be refilled or replaced.
Sealed electrodes cost less and are easy to use, but they must be replaced when they dry out.
Refillable electrodes can be soaked in the filling solution to extend the life of the electrode.
"The three common types of pH meters are pen-style, handheld, and benchtop meters. "
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pH meter features
Backlight
A backlight can make the LCD of a pH meter easier to read in dark — and very bright — environments, ensuring that you don’t misread the screen. This feature can be found in many pen-style and handheld models.
Additional measurements
Some pH meters are capable of gathering additional measurements from substances. In some cases, this is done simultaneously with pH readings. With most models, the meter must be switched to a different mode to take the reading.
Additional measurements may include the following.
- Temperature
- Conductivity
- Oxidation-reduction potential (ORP)
- Total dissolved solids (TDS)
- Salinity
pH meter prices
Entry-level pH meters for $5 to $50 are usually pen-style meters with sealed electrodes. These meters are typically limited to reading only pH and are usually calibrated automatically. Most soil pH meters fall in this range.
Midrange pH meters, $50 to $100, will be pen-style and handheld models suited to hobbies like beer brewing and wine making. These meters may be more robust, with a few waterproof and shockproof models available in this range.
High-end pH meters that cost $100 to $500 may be pen-style, handheld, or benchtop models. Meters in this range may be capable of measuring temperature, ORP, and other qualities of substances. Lab-ready meters are usually found for $300 to $400.
Did you know?
A pH meter measures the pH of a substance by measuring its voltage and comparing it with the voltage of buffer solutions.
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Tips
- Measuring liquids or surfaces that are very hot or cold could damage your pH meter.
- The electrode of your pH meter needs to be cleaned after every use.
- Never touch the electrode, as it could easily become damaged.
FAQ
Q. How do I clean the electrode probe of my pH meter?
A. The electrode should be wiped with a clean cloth and ionized water after every use.
Q. How often do I need to calibrate my pH meter?
A. A pH meter should be calibrated about once a week. However, this may vary from one model to the next. For best results, check the instructions provided by the manufacturer.
Q. When should pH tabs be used instead of a pH meter?
A. A pH meter is almost always more accurate than pH tabs and can be used over and over. If you only need to determine the pH of something a few times, pH tabs may suit your needs. But any serious brewer or cheesemaker will need a reliable pH meter.
Q. How do you store a pH meter?
A. In order to keep the electrode from drying out, most pH meters come with a storage solution that goes in the cap. This keeps the electrode moist.
