Hi
Yes 1L is the instructed and required amount to get optimum accuracy.
Here is the copy and paste from the instructions
1. Set the desired Max.Speed of the pump.
2. Provide two roughly equal measuring containers and fill one with water (about 1 liter). Now turn the suction tube into the filled container and the other one into the empty container. Go to the GHL Control Center and click on calibrate the pump now. Follow the instructions.
3. After the procedure is completed, measure the amount of water that was pumped into the empty container and add the value to Flowrate of the pump in the GHL Control Center.
If you need more help just let us know or email me at
info@ghlna.com