Why Hydroponic Growers Use pH 4 and pH 7 Calibration Solutions?
Intro
I have started with hydroponics a long time ago, and the first thing everyone told me was:
You’ve got to keep the pH stable.
There is a full article about why pH is so important, but in this one, we’ll get a bit more technical.
At Growee, we offer a complete pack that includes pH and EC probes as well as their calibration solutions. (For EC calibration, we’ll cover it in a different article.)
How Do I Know If My pH Probe Needs to Be Calibrated?
This part is very simple.
Before you go and calibrate, just verify:
Place the pH probe inside the pH 7 solution and see if the reading is between 6.9–7.1.
Most pH pens and monitoring devices have a tolerance of ±0.1.
If the reading is within range, in most cases you don’t need to calibrate.
However, it’s still a good idea to test the values also in the pH 4 solution to confirm accuracy across the range.
How Do I Know If My pH Probe Needs to Be Calibrated?
In hydroponics, soilless growing, and agriculture in general, the water pH should be around 6.0.
It could be slightly lower or higher depending on the plant type and growth stage.
Some plants prefer lower pH (like blueberries, for example), but in most cases 5.8–6.2 is the sweet spot that allows all nutrients to be absorbed by the plant’s roots.
You can find pH 10 solutions on the market, but they are far outside the cultivation range and not suitable for our application. That’s why it became an industry standard to calibrate using pH 4 and pH 7 solutions.
Cleaning and Maintenance
Before you go and verify the pH calibration, make sure the probe is clean.
In cases where the probe is fully submerged in water, like in the Growee Smart Dosing System for hydroponics, there might be some buildup around the probe bulb.
Don’t panic! Just wash it gently with a soft toothbrush and you’re good to go.
How Temperature Affects pH Calibration?
In contrast to EC calibration (which we’ll cover in another article), pH is not very sensitive to temperature changes.
As long as your calibration solutions are between 68–82°F (20–28°C), you can start the calibration without worries.
If you’re looking for the official Growee calibration kit, including pH 4.01, pH 7.00, and EC 1413 μS/cm solutions with replacement probes, check it out here
