Atlas Scientific EZO PH Calibration Procedure

Introduction: Atlas Scientific EZO PH Calibration Procedure

About: Founded in 2005, Atlas Scientific specializes in building laboratory grade sensing equipment for robots, appliances, and industrial control systems. Thousands of Atlas Scientific sensors can be found in a wide…

This tutorial describes the calibration procedure. It is assumed that the user has their hardware and code working and is now ready to calibrate the sensor.

Theory

The most important part of calibration is watching the readings during the calibration process. It is easiest to calibrate the device in its default state (UART mode, with continuous readings enabled). Switching the device to I2C mode after calibration will not affect the stored calibration. If the device must be calibrated in I2C mode, be sure to continuously request readings so you can see the output from the probe. For instructions on how to change between protocols refer to: How to change data protocol of Atlas sensors

The Atlas EZO pH circuit has a flexible calibration protocol, allowing for single-point, two-point or three-point calibration. If this is the first-time calibrating the EZO pH circuit, it is recommended that you calibrate in the following order:

Mid-point (pH 7) --> Low point (pH 4) --> High point (pH 10)

Two-point calibration will provide high accuracy between 7.00 and the second point calibrated against such as 4.00. Three-point calibration will provide high accuracy over the full pH range. Three-point calibration at 4.00, 7.00 and 10.00 should be considered the standard.

Doing a mid-point calibration after the pH circuit has been calibrated will clear the other calibration points. Hence the mid-point must be done first.

Step 1: Mid-Point Calibration

a) Enable continuous readings.

b) Remove the soaker bottle and rinse off the pH probe.

c) Pour some of the pH 7.00 calibration solution into a cup. Ensure that there is enough solution to cover the sensing area of the probe.

d) Place the pH probe into the cup and stir it around to remove trapped air. Let the probe sit in the calibration solution until the readings stabilize (small movement from one reading to the next is normal).

e) Once the readings have stabilized (1-2 minutes) issue the mid-point calibration command cal,mid,7

Step 2: Low-Point Calibration

a) Rinse off the probe before calibrating to the low point.

b) Pour some of the pH 4.00 calibration solution into a cup. Ensure that there is enough solution to cover the sensing area of the probe.

c) Place the pH probe into the cup and stir it around to remove trapped air. Let the probe sit in the calibration solution until the readings stabilize (small movement from one reading to the next is normal).

d) Once the readings have stabilized (1-2 minutes) issue the low-point calibration command cal,low,4

Step 3: High-Point Calibration

a) Rinse off the probe before calibrating to the highpoint.

b) Pour some of the pH 10.00 calibration solution into a cup. Ensure that there is enough solution to cover the sensing area of the probe.

c) Place the pH probe into the cup and stir it around to remove trapped air. Let the probe sit in the calibration solution until the readings stabilize (small movement from one reading to the next is normal).

d) Once the readings have stabilized (1-2 minutes) issue the high-point calibration command cal,high,10

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    2 Comments

    0
    KyleH62
    KyleH62

    Question 4 months ago on Introduction

    I have the Atlas hydroponic wifi kit and cannot get it to calibrate. I really need some help. I've read and followed this and every other Atlas data sheet. Staring with the poll cmd it shows rtm at 19C pH 14 and EC at 0 doesn't change, then I run the pH mid 7 cmd and then poll cmd rtm 19C pH 7.00 EC 0 and move on to the 4.00 pH solution and look at the serial monitor yo see it reads 6.99 pH and it stays the same each second 7.00 6.99, it's the same if I try th 10 pH solution. Now I have a $450 pH kit and now way to read the pH in my greenhouse :(

    0
    CB71
    CB71

    Answer 7 days ago

    I have the Atlas hydro kit and called them many of times. I ended up speaking with Jordon, he was a great help.