To calibrate the aquarium pump please follow these steps:
Make sure the plastic filter is submerged in water
Put the exit tube coming from the pump to the measuring beaker
Fully fill the tubes using FILL THE CIRCUIT button
Please empty the measuring beaker if any water is present
Start the calibration process
When the pump stops please measure the amount that it is in the beaker and put the value in the box
Check if the pump is calibrated correctly.
To do this put the tube into the empty measuring cup and use TEST THE ACCURACY button. The difference should not be greater than 0,5 ml.
Here is the video about the calibration: