There are so many moving parts to a successful grow room that having the right tools is essential. One of the most essential pieces of equipment is a high-quality pH or PPM pen. 

If your plants are experiencing nutrient deficiencies, the reason could be that the pH is all wrong. Even if you’re pumping them full of nutrients, a pH that is too high or too low can stunt growth and ruin potency. 

Some growers are lucky and can get by without worrying about soil and water pH levels, but this is extremely rare. Even if you’ve had success without using a pH pen or PPM meter in the past, you shouldn’t be growing without one.

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How to Choose a pH Pen or Meter

One question that we get all the time at CGC is “what’s the best pH pen?”… The answer isn’t simple since it depends on things like budget and plant counts, but we do have one piece of advice for choosing the right one. 

There are several types of pH testers to choose from, including digital pens, test strips, and pH-testing drops. Although the strips and drops come in handy from time to time, our suggestion is to always go with the digital pen design. 

Another piece of advice is to fully understand the difference between a pH pen and a PPM/TDS meter. These are completely different tools (we’ll talk about this later), so make sure you’re buying the right one. 

Things to Consider When Choosing a pH or PPM Pen

Testing pH doesn’t have to feel like a confusing science experiment – especially when you follow these considerations to choose the right pH pen or PPM meter. 


A high-quality digital pH meter is made with durable components and will last for many grows to come. Try to stay away from the cheap Chinese-made products; these are much more likely to break after 1 or 2 harvests. 

Ease of Use

Measuring your crop’s pH or PPM value should be easy. Some old-school growers stay loyal to pH strips and drops for their simplicity but trust us when we tell you that digital pens are just as easy to use (when you choose the right one). 

Added Features

Your best bet is choosing a digital pen that includes both pH and PPM readouts. If you’re willing to spend a bit extra, look for automatic calibration and included calibration fluid. 


If you’re on board with the digital pen design, try to stray away from anything under $40. Sure, the low price may be tempting, but the low price means low-quality cheap pH pens. Measuring pH is a major aspect of a successful harvest, so the extra $20 or $30 is well worth it. 

Best Overall Combo pH & PPM Pen for Perfect Plants

As growers ourselves, the team at CGC has tried and tested a huge variety of pH and PPM tools. There are a lot of good choices on the market, but there’s one that outshines the rest when it comes to accuracy, durability, and ease of use.

Bluelab BLU2300E Combo Meter 



The Bluelab BLU2300E Combo meter doesn’t just work to measure pH. It measures everything you could ever need to know about a liquid, including pH, electrical current, temperature, PPM, and conductivity factor. 

This lightweight all-in-one device truly does it all, it even has simple automatic calibration to ensure accuracy with each pH reading. This is without a doubt the best pH PPM measurement tool on the market, but it’s not ideal for budget growers. 

Best Bluelab PPM Pens & pH Meters

Bluelab products are the most reliable devices for measuring grow room pH. If you’re looking for something that doesn’t break the bank like the 2300E Combo Meter, here are two more top-rated options from Bluelab. 

Bluelab BLU2210 pH Pen



The BLU2210 pH Pen from Bluelab measures pH and temperature and has an indicator for a successful calibration. A lot of growers in Canada feel that these features are all you need for measuring pH since acidity/alkalinity and temperature are two main factors in plant growth. 

The main downside of the BLU2210 is that it does not measure PPM, so we suggest investing in a separate PPM meter for measuring nutrients in the water. As long as you’re strictly looking for pH and temperature measurements, this is a handy Bluelab. 

Bluelab PPM Pen 



If you’ve got your heart set on the BLU2210, but don’t love that it doesn’t come with a PPM readout, the Bluelab PPM Pen is the perfect solution. This compact device measures conductivity and temperature, it’s fully waterproof, and it has a bright backlit LCD. 

This is NOT a pH pen, so you’ll have to look elsewhere for your pH measurements. This tool is mainly used for measuring added nutrients in your water solutions, helping growers to avoid over or under-doing it with nutrients.

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Best pH Pen for Cannabis Growers on a Budget

Grow room expenses add up quickly, especially after buying the major pieces of equipment like lights and ballasts. The good news is that you don’t need to dish out tons of cash on a high-quality pH meter. 




The HM Digital pH meter is the most budget-friendly on this list of best pH and PPM tools. Bluelab will always be our favourite, but unfortunately, the high quality of Bluelab products does not come cheap. This tool is the next best thing for measuring pH on a budget. 

The HM meter measures both pH and temperature, it comes with one-touch automatic digital calibration, and it’s amazingly accurate for the low price tag. You can’t measure PPM with this device, so you’ll need to invest in a different tool for that (like the Bluelab PPM Pen). 

Best Budget Combo pH & PPM Meters

There’s nothing better than using a single tool that performs two separate functions. Using a combo pH and PPM meter keeps things simple, which is all that a grower can ask for. 

Apera AI209-T PH20



The Apera AI209-T comes with a complete calibration and probe care kit, so you can expect to get a lot of use out of this pH PPM pen. Apera is all about reliability and accuracy, which is why they focus on making calibration so easy. 

One thing we’re loving about the AI209-T is the included CalBox to help growers stay organized. This box holds up to four containers for different solutions, and it has been proven to save on buffer solution costs by up to 50%. 

Bluelab Guardian Monitor 



This next one is by no means a budget-friendly pH/PPM monitoring tool, but trust us when we tell you that it’s worth every penny. The Bluelab Guardian Monitor measures pH, conductivity, and temperature in one easy-to-use device. 

Don’t be fooled by the product description on Amazon; it says “for plant germination”, but the Guardian Monitor can (and should) be used for all phases of the grow. Calibration can be completed with one push of a button, and growers say that this tool gives the most accurate results. 

Best Digital pH Pens

Digital pH pens for water and liquid solutions aren’t hard to come by, but some take the word digital to a whole new level. Some of the best digital pH pens on the market come with Bluetooth connectivity, like the PC60-Z device. 

PC60-Z Bluetooth 



The PC60-Z Bluetooth digital pH pen professionally measures pH, conductivity, TDS, salinity, and temperature. But the thorough measurements aren’t even the best part of this device; it serves as a cloud-based data management system for your grow op.

This cloud-based allows you to record, manage, and share test info, but more importantly, you never have to worry about losing grow op data. Some growers find it difficult to use, but if you consider yourself tech-savvy, you’ll have no trouble with the PC60-Z. 

Best pH Pens for Water & Soil

Finding pH pens for water and soil isn’t always easy – most pH pens are strictly for use in liquid solutions, so soil testing is out of the question. This isn’t the case for the Bluelab PENSOILPH Soil Tester. 

Bluelab PENSOILPH Soil Tester 



The Bluelab Soil Tester allows growers to directly test the pH of plant soil. This means you no longer have to test the water runoff of your soil – just stick the pen into the plant pot for an accurate pH readout.

The PENSOILPH pen isn’t strictly for soil testing, but it can be used in other growing media and liquid solutions as well. Unfortunately, it’s not suitable for measuring distilled, RO, or de-ionized water since the ionic strength of these liquids is too low for the meter to pick up pH readings. 

Why is it important to monitor pH levels?

Grow room pH that is too high or too low is the most common cause of plant nutrient deficiency. If the soil/water is too alkaline or too acidic, they won’t be able to properly absorb nutrients. 

By maintaining the slightly acidic pH level that cannabis plants tend to thrive in, they’re much less likely to suffer from nutrient deficiencies and leaf problems. And best of all is the fact that healthy nutrient absorption goes hand-in-hand with bigger yields. 

How to Use a pH Pen

There are 3 main steps to using digital pH testing pens: 

  1. Calibration
  2. Measurement
  3. Cleaning/Storage


Calibration can be a bit tricky, so be sure to read your pen’s user manual to follow the right steps. The best way to test your pen’s accuracy after calibrating is to use a solution with known pH value, like 4.01 and 7.01. If the pen gives an inaccurate reading, it’s time to calibrate. 


After calibrating, measuring the pH of your grow room should be easy. Take the pen cap off, turn the pen on, and place the pen’s electrode in the liquid you’re testing. Once the numbers on the display screen stop fluctuating, you have your pH reading. 

If your pen is measuring on the slow side, try gently swirling the electrode in the water – the keyword here being gently. For hydroponic growing, pH should range between 5.5 to 6.5. For soil growing, a higher pH of 6.0 to 7.0 is ideal. 


Proper cleaning and storage is a major aspect of using a pH pen. If you fail to clean and store your device properly, don’t expect to get a lot of use out of it. 

After measuring, clean the electrode with the included cleaning solution. If you don’t have a cleaning solution, the next best thing is distilled water. 

For storing, pour a small amount of the included storage solution into the pen’s protective cap (enough to cover the electrode when the cap is on). Then, securely place the cap on, turn the device off, and keep it in a safe place until your next pH measurement.

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How to Calibrate a pH Pen

We’ve already covered the basics of calibration, but let’s go into more detail on manual vs automatic calibrating. A pH PPM pen with manual calibration is less convenient, but the steps are pretty simple. 

Pour a bit of 4.01 pH solution into a container. With the pen turned on, place the electrode in the solution, swirl it around a bit, and wait for a reading. If it’s anything other than 4.01, press the appropriate up/down buttons until it reads 4.01. You’ll do the same thing with a 7.01 pH solution. 

Good pH pens for marijuana come with much simpler automatic calibration. You’ll still dip the electrode in 4.01 and 7.01 solutions, but you won’t have to push any buttons or spin any dials to manually calibrate. The device will calibrate on its own. 

Difference Between pH and PPM Pens and Meters

While a pH pen measures the alkalinity/acidity of a liquid solution, a PPM (parts per million) pen measures the total dissolved solids in a liquid. PPM and TDS meters are the same, both measuring how much “stuff” is in a liquid. 


Our suggestion is to buy a pH PPM pen combo that tells you all about the liquid’s content, like the BLU2300E Combo Meter. Out of all the most reliable TDS pH pens, this tool can make a massive difference in your next harvest’s yield.

Don’t forget to check out our articles on reverse osmosis for cannabis growing and our guide to growing cannabis indoors for more information.

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