The Best Digital pH Meters, Test Kits, and Accessories

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Hydroponic gardening can feel a lot less like traditional gardening and a lot more like an undergraduate level science class at times.

Unlike soil based gardening, growers need to keep track of every little detail, from ventilation to the pH level of their system. Failure to properly monitor one part of your system can result in sickly plants and a healthy dose of frustration for you – trust me, I know.

When I first got into hydroponics, I didn’t take pH measuring seriously. I was used to soil gardening, where a few soil tests every few years and a stockpile of lime and compost kept my soil right where I wanted it.

I quickly found out that hydroponic gardening required a little more attention to detail, which is why investing in the best pH meters, pens, and testing kits is worth your while.

If you just want to know the best pH products in each category, I’ve listed them here. Otherwise, check out the rest of the article:

Digital pH Meters

Digital Combo Meters

Why Monitoring Your pH is so Important

The pH scale and where different household items are on the scale. source

So why does pH matter? The pH of any growing system, be it hydroponic or soil, plays a large role in the growth of your plants. It’s not just a matter of some plants preferring more acidic soils or other plants preferring more alkaline – pH determines the nutrients that are available to your plants.

Look at it this way: you take the time to ensure your plants get all of the nutrients that they need. But none of this matters if your pH is off. Unless your pH is in the right range, your plants won’t be able to absorb the nutrients, which means you have wasted time and money adding them to your system.

Still confused? Check out my article on pH and nutrient availability for a complete breakdown of the relationship between pH and nutrient availability.

But for now, what you need to know is that pH matters, and you need to monitor it.

Most plants do well with a pH of 5.5 to 6.5. While some plants have specific requirements, a good rule of thumb is to stick to the “sweet spot,” which is a pH of 6.2.

Keeping your system slightly acidic has another advantage as well: many waterborne algae varieties don’t like acidic environments. Since we don’t like waterborne algae, this is a win-win situation.

How Does a pH Meter Measure pH?

Now that we agree that monitoring pH is crucial to the growth of your hydroponic garden, let’s talk about how pH meters work.

Your pH meter measures the hydrogen-ion concentration of your water. This concentration indicates whether the solution is acidic or alkaline by determining the difference of the electrical potential between a reference electrode and a pH electrode.

Personally, my brain has a hard time wrapping around this sort of thing, so I’ll keep it simple. Your meter has a glass electrode, which is sensitive to hydrogen ions, and a reference electrode, which is stable. The difference between the two tells the pH meter what the pH of the liquid is and allows you to adjust the pH accordingly.

Manual pH Testing vs. Digital pH Meters

There are two basic types of pH meters: manual and digital. If you are a serious hydroponic grower, then you probably already use a digital pH meter. If you are just getting started, though, I will give you the breakdown of the pros and cons of manual pH testing vs. digital.

Manual pH testing

pH strips
Typical manual pH testing kit.

Manual pH testing is done with a simple kit, kind of like the water pH test kit you use to test the pH of a pool. Manual water pH test kits are much cheaper than digital pH meters and they are easy to use.

Upsides to Testing Your pH Manually

Since there are no parts to a manual pH kit that require care, you don’t need to worry about things breaking or corroding over time. These traits make manual testing kits ideal for growers just getting started in hydroponics.

Downsides to Manual pH Testing​

The downsides of manual pH testing make them less than ideal for serious growers. It takes a lot more time and effort to work with manual pH test strips or pH fluid, like the kind in the General Hydroponics kit we will discuss in the review section below.

Time management becomes a barrier to serious growers, especially when compared to the simplicity of a digital pH meter.

Accuracy is also an issue. PH strips can be hard to read, especially if you are color blind. This can lead to pH readings that are way off, which will negatively impact your system.

Digital pH meters

Bluelab pH Pen

Digital pH meters are the way to go it you plan on doing a lot of hydroponic growing. These meters should last a lifetime if you take care of them, and they are much more accurate than manual pH meters and pH test strips if they are calibrated properly.

Digital meters are fast, too, letting you test quickly and frequently, making them far more efficient than manual pH meters.

Downsides to Digital pH Meters​

Of course, all of this convenience and efficiency comes at a price. The best digital pH meters are more expensive than manual pH meters, and they also require more maintenance than manual meters.

Digital pH meters must be calibrated frequently in order for them to remain accurate, and without proper care, your expensive digital pH meter breaks down.

Calibrating a pH Meter

If you choose to go the digital route, as most of us eventually do, you need to know how to calibrate your pH meter. Think of calibration like tuning a musical instrument. You need things to be tuned to the right key, or the entire musical piece will be off.

Before you begin, you need a buffer solution. A buffer solution is basically a laboratory certified standard reference point for your pH meter. Most buffer solutions are liquid, although you can buy them in powder form and mix them with distilled water if you prefer.

Once you have your buffer solution, follow these steps to calibrate your pH meter:

  1. Place your meter into the buffer solution to get a reading
  2. Adjust the reading on your meter to match the buffer solution according to the manufacturer’s instructions (these can differ for digital and analog meters)
  3. Repeat if necessary in an additional buffer solution of a different pH for higher accuracy
  4. Calibrate your pH meter once a week if you use it regularly, or at least once a month
  5. Always calibrate your pH meter when you replace a sensor or if you think the reading is inaccurateYour pH meter will come with instructions. Make sure you read them before calibrating your meter just in case the steps are different.​

You can also watch this video guide from my friends at GrowAce on calibration if you’re more of a visual person:

Caring for your pH Meter

All of that calibration won’t matter if you don’t take the time to care for your pH meter.

As boring as most directions usually are, the first thing you should do when you get a new pH meter is read the instruction manual that comes with it. The instructions should tell you how to care for your pH meter. If they don’t, call the manufacturer and ask them.

In general, there are several things you need to do for every pH meter:

  • Read the instructions
  • Keep it calibrated
  • Store meters with storage solutions in the cap upright for optimum saturation
  • Lightly swirl your meter in the storage solution to get rid of air bubbles
  • Don’t touch the sensor electrode or reference cell, as the oil on your skin can damage the sensor and affect readings
  • Store away from high heat and humidity
  • Don’t store your sensor in distilled water
  • Handle with care

The Best Manual pH Testing Kits

Sale
General Hydroponics pH Control Kit
  • Designed to work superbly in hydroponic environments, both...
  • Includes pH Test Indicator tube:fill a test-tube halfway...
  • Includes 8oz bottle of pH Up which is used to elevate it to...
  • Contains 8oz bottle of pH down which uses food grade...
  • For best results, discard and replace hydroponic solution...

Manual pH test kits are great for beginners or for growers on a budget. If you decide to go with a manual kit, the best choice is the General Hydroponics pH Testing Kit.

This pH test kit is designed especially for hydroponic environments and comes with an 8oz bottle of both pH up and pH down to help you adjust the level of your system, along with a pipette, a pH test indicator tube and the 1 oz bottle of pH test indicator itself.

Pros

  • Easy to use
  • Comes with pH Up and pH Down to adjust the pH level
  • Works in hydroponic environments with soil-less mixtures and soil grown plants

Cons

  • The price is a little higher than some of the other options
  • Only comes with one pipette, so you might want to buy another to prevent cross contamination with bases and acids

If you are looking for a slightly cheaper pH test kit, take a look at these litmus pH test strips designed for universal application. These pH test strips are more economical than the kit, but the kit is a better value for your money and is slightly more accurate.

See Prices


The Best Digital pH Meters

There are a lot of digital pH meters on the market. We recommend either the Bluelab pH Pen or the Oakton EcoTestr.

The Bluelab pH Pen​

Bluelab PENPH pH Pen for Plant Germination
  • Measures pH and Temperature
  • Backlit LCD display
  • Successful pH calibration indicator
  • Fully waterproof
  • Automatic Temperature Compensation

The Bluelab pH pen is one of the best pH pens out there. It measures pH and temperature, and the back-lit LCD display makes it easy to read. I’ve written a more in-depth review of the Bluelab pH pen here, but the basic idea is that it’s my favorite digital pH meter and the one I use in my gardens on a daily basis.

Pros

  • Easily measure pH and temperature with one reading
  • Fully waterproof
  • Sponge in cap to keep the probe moist
  • Comes with 1-year warranty

Cons

  • More expensive than most pH pens
  • Calibration kit not included
  • Fragile sensor bulbs

See Prices


The Oakton EcoTestr

Sale
Oakton EcoTestr pH 2 Waterproof pH Tester, 0.0 to 14.0 pH Range
  • Push-button calibration capabilities up to three points for...
  • Automatic Temperature Compensation (ATC) for accurate...
  • Transparent, protective cap keeps sensor moist when stored...
  • Waterproof, dustproof housing is Ingress Protection (IP)...
  • Large, upright, single-line LCD display screen for ease of...

The Oakton EcoTestr is cheaper than the Bluelab pH Pen, making it one of the best digital pH meters for the money. If I was just starting out growing hydroponically, I’d probably opt for the Oakton as it’s a bit cheaper and has most of the functionality that I need in a pH meter.

Pros

  • Good budget option
  • Measures pH and temperature
  • Waterproof and dust proof
  • Convenient pocket size
  • 1-year limited warranty

Cons

  • Doesn’t last as long as the Bluelab pH pen
  • Must keep calibrated more often

See Prices

If neither of those options fit your needs or budget, two similar digital pH meters to look into are the Milwaukee Instruments pH55 tester and the Hanna Instruments Grochek.


The Best Digital pH Combo Meters

Some growers need a meter that does more than monitor pH. Digital combo meters measure pH, temperature, and other important garden metrics.

Combo meters are more expensive, but when you consider the cost of buying a meter for each individual reading, they make a lot of sense if you’re a more serious grower that wants all of your important readings in one place. ​

Bluelab Combo Meter

Bluelab 716441 Combo Meter for Plant Germination
  • Measures pH, temperature and EC, ppm 500, ppm 700 and CF
  • Lightweight and portable.Probe cable length: 6.5 feet
  • Successful pH calibration indicator
  • Replaceable Double Junction pH Probe included
  • Auto off function. Please see page 3 onwards for set up...

The Bluelab Combo Meter is the de-facto standard in combination pH, temperature, and PPM/EC/TDS meters. It’s the one that I recommend most often as well as the one that I find most growers to be satisfied with.

Pros

  • Measures pH, temperature, and electroconductivity (EC)
  • Comes with replaceable double junction pH probe
  • Auto off function

Cons

  • Fragile probe
  • Not waterproof

See Prices


Hanna Instruments pH/EC/TDS/Temperature Meter

Hanna Instruments HI 9813-6N Waterproof pH/EC/TDS Temperature Meter Clean and Calibration Check for...
  • Starter set with portable, water-resistant meter for testing...
  • Calibration check function to validate instrument...
  • Automatic temperature compensation (ATC) to eliminate the...
  • Alert system when low battery and potential measurement...
  • On-screen user and calibration guides

If for some reason you don’t like the Bluelab line, the Hanna combo meter is a great alternative. Hanna is another extremely reputable manufacturer of pH and combo meters, and although I personally use Bluelab, many of my friends are devoted Hanna fans.

One of the best features in this combo meter is the built-in calibration reminder. No more forgetting to calibrate and wondering why your readings are so off!

Pros

  • Measures pH, temperature, electroconductivity (EC), and total dissolved solids (TDS)
  • Easy to read display
  • Simple operation and calibration
  • Built in calibration reminder
  • 7.0 and 4.0 calibration
  • Waterproof

Cons

  • Cap has no seal lock
  • No anti-slip feet

See Prices


Bluelab Guardian

Sale
Bluelab BLU27100 Guardian Monitor for Plant Germination
  • Large easy to read green led displays
  • Selectable values for conductivity and temperature
  • Flashing high and low alarms
  • Greater tolerance to rf/electronic interference provided
  • Simple push button ph. calibration.A flashing display means...

The best combo meter is the Bluelab Guardian Monitor. This meter is pricier than the other options but is ideal for serious growers with a large budget. Because it’s always on and monitoring your garden, you’ll know the instant that your metrics get out of whack.

If you are a larger-scale grower with some money to invest in your monitoring system, then you absolutely must go with the Bluelab Guardian. I know of no other good solution for this level of live-monitoring.​

Pros

  • Large, easy to read displays
  • Flashing alarms if numbers are out of range
  • Comes with a range of accessories

Cons

  • Sometimes the digital displays bug out (only a few reports of this)
  • You can burn through probes quickly without proper care and calibration

See Prices


Helpful pH Testing Accessories

After dropping a large sum of money on a digital meter, I’m sure that last thing you want to think about is buying more accessories.

Unfortunately, your meter won’t be much use to you without a calibration solution and care kit. These kits help keep your pH meter accurate and operational, giving you better results and preserving your investments.

Bluelab Probe Care Kit

Bluelab Probe Care Kit
  • Pack contains 2 x 20ml sachets each of pH 7.0, pH 4.0 and...
  • PH probe cleaner included
  • PH probe cleaning tool included
  • Plastic cups included
  • Full instructions included

If you decided on a digital pH meter from Bluelab, their probe care kit is both affordable and the best option. It’s designed to work with the full range of Bluelab products, and comes with a bottle of 4.01 reference solution and 7.0 reference solution, available in 8 oz and 1 quart quantities.

Pros

  • Designed for use with Bluelab products
  • Comes with proble cleaner, tool, and plastic cups

Cons

  • Only comes with 2 x 20ml sachets

See Prices


General Hydroponics pH 4.01 & pH 7.0 Calibration Solution

General Hydroponics Ph 4.01 & Ph 7.0 Calibration Solution Kit, 8 oz
  • 2 bottles - 1 each of Ph 4.01 & Ph 7.0 Calibration Solution
  • Highest quality electronic meter reference solutions
  • Each batch is checked to ensure calibration

General Hydroponics also has a calibration solution kit that comes with one bottle of pH 4.01 solution and one bottle of pH 7.0 solution. This is a good option if you either don’t have a Bluelab meter, or you just want a large quantity of calibration solution without any of the extra bells and whistles.

Pros

  • General Hydroponics is a highly reputable brand in hydroponics
  • You get much more calibration solution for the money

Cons

  • Does not come with cleaning supplies

See Prices


All of this might seem like a lot of information to take in, but I promise it is worth it.

Monitoring the pH of your hydroponic solution is the single most important thing you can do to ensure a thriving crop and happy plants.

To do that, you need the right tools, and you need to know how to care for them.

One of the things I have learned as a gardener is that there are two things that can ruin a tool: buying a cheap, poorly made product and failing to care for it properly. If you have invested time and money into your hydroponic system, don’t waste it by buying a cheap pH meter.

A good meter will pay back your investment, and a bad one will cost you more in the long run.

I hope you found this review helpful. Please feel free to share any comments or insights in the comment section below.


The Green Thumbs Behind This Article:


Kevin Espiritu
Founder

Tracking the pH of your garden is the key to a good harvest. Read my in-depth reviews of the best digital pH meters, testing kits, and accessories.
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5 thoughts on “The Best Digital pH Meters, Test Kits, and Accessories”

  1. In the previous comment I meant I have NOT found an answer to the pesticide/environmental toxin question. So if you have an answer, I’m very pleased. Thanks!

    • I hear you on this Rick. It’s important to pick as high-quality a supplier as you can and then for the rest of it, let it be. There’s only so far you can go on the toxin thing before coming to the conclusion that you must grow and create your own coconut coir :p – which almost no one will do.

  2. Hi, very good article. One thing I have found an answer to: What about pesticides? I understand that coconut farmers use quite a lot of pesticides when cultivating pesticides. Don’t they leave harmful traces in the coir? Soaking in the manufacturing process propably takes care of some of it, but tidal waters also have environmental toxins in them. Is the coir safe to use when farming food for yourself?

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