How to Calibrate and Use a pH Meter

An in-depth guide for beginners on how to calibrate and use a ph meter. Discover how to set up a ph meter and use it in a few easy to follow steps.

How to Calibrate and Use a pH Meter Cover PhotoWhether you recently purchased a new pH meter or you’re thinking of pulling the trigger on one — you must learn how to calibrate and use a pH meter.

You may ask, well, how hard can it be?

Considering we’re flooded continuously with pH related questions, we’re going to go ahead and show you how to set up a pH pen in a few simple steps. Don’t worry — the entire step-by-step process of setting up a pH meter lasts a few short moments.

Once your pH meter is ready to go — it’s time to watch your marijuana beauties stack on the weight.

Let’s begin!

How To Calibrate a pH Meter in Five Easy Steps

Want to get accurate pH readings all day long?

There’s only one way to get pinpoint pH readings, and that’s through calibration. Calibration is the process of setting up your device to measure under a set of standards.

In the case of pH meter calibration, you must calibrate your pH pen according to three primary points of standardization:

  • Acidic
  • Neutral
  • Basic

Before we begin, you must have a few tools on-hand, such as:

  • pH meter
  • pH four calibration liquid
  • pH seven calibration liquid
  • pH ten calibration liquid
  • Glass measuring cup (Pyrex)
  • Gloves
  • Protective eyewear
  • Distilled Water
  • The pH meter’s instruction manual

Alright, now that you have all of these essential tools, let’s get your pH meter calibrated.

Step One: Organization

First and foremost, organize all of your tools in a clean area. Remember, you want to make sure there isn’t anything on the pH meter or glass measuring cup to skew the results.

Now that everything is ready turn on the pH meter.

Step Two: Enter Calibration Mode

Once the pH meter is on (depending on the brand), open up the instruction manual.

ph meter calibration button

The instructions should show you which button to press to enter calibration mode. Now, put on your gloves and pour a small amount (quarter cup) of pH four calibration solution into the glass measuring container.

Remember, pH 4 is acidic and may irritate your skin if you touch it without gloves. Please, be careful while handling the calibration solution!

Step Three: Calibrating pH 4

Next, dip the pH meter (it must be in calibration mode) into the pH four calibration solution.

Suppose the pH meter reads 4.0 — success! However, if the meter does not read 4.0, you must manually set the meter to 4.0. If the pH meter does not align with the calibration solution, it’s safe to say the pH meter is uncalibrated and inaccurate.
pH Calibration 4

Step Four: Calibrating pH 7 & 10

Repeat steps two and three for pH seven and pH ten calibration solutions.

Remember — you must:

  • Clean the pH meter’s probe in between testing (rinse the probe with distilled water after each use)
  • Never mix calibration solutions

Step Five: Calibration Complete

Once your pH meter coincides with each calibration solution (pH 4, 7, and 10) — you’re officially ready to begin using your pH pen!

How to Use a pH Meter in Three Easy Steps

Now that you’re good to go — let’s talk about using your newly calibrated pH meter.

Using a pH meter is incredibly easy once you learn how to dip, adjust, and finalize.

Here’s a list of tools that you’ll need when using your pH meter:

  • pH meter (duh)
  • pH up solution
  • pH down solution
  • Gloves
  • Protective eyewear
  • Plastic syringe (to dispense pH up or down)

*As an important note, this guide focuses solely on cannabis plants grown in hydroponic or soilless media.

Step One — Dip

So, your marijuana plants are looking hungry — it’s time to mix up some bottled nutrient solution.

Mixing nutrient solution is easy as pie — simply check the recommended dose from the manufacturer and mix it with a predetermined amount of water.

However, bottled nutrients are composed of salt, which alters the pH level of tap or bottled water. Therefore — we need to break out the pH meter and dip it into the nutrient solution to gain insight into its current pH.

Therefore, once you’ve mixed nutrient and water, the first step is to dip the pH pen and take a reading.

Unless your pH reading shows 5.2-5.5 — you’ll need to adjust it.

Step Two — Adjust

So, your pH reading is 6.0 or 7.2. Regardless, you must adjust the pH of the nutrient solution before you feed your weed plants.

To adjust the pH reading, you must use a pH up or down solution to get to the optimal zone – 5.2-5.5 pH.

pH up is a concentrated acidic solution, and pH down is a concentrated basic solution. Therefore, apply small amounts depending on your desired direction.
To adjust pH:

  • Apply 1ml of pH up or down to one gallon of nutrient solution
  • Wait for 15-30-minutes
  • Take a reading
  • Fine-tune pH with additional drops of pH up or down

Step Three — Finalize

After 30-minutes, it’s time to finalize the nutrient solution.

Use your pH meter and take a reading. As long as the pH value does not fluctuate and remains within the optimal range (pH 5.2-5.5) — you’re good to go!

All that’s left to do at this point is feed your marijuana plants. As you can see, it’s effortless to use a pH meter.

Never Feed Cannabis Plants Without a pH Meter

There you have it!

There’s no reason why you should ever feed your cannabis plants non-pH’d food with instructions this easy. Unless you’re trying to kill your weed crop, always have a calibrated pH meter on hand.

As your cannabis garden grows, you’ll notice lush, green growth and booming buds that’ll soon knock your socks off.

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