Are you using the Atlas Scientific dosing pumps? The reason I'm asking is that I'm working on a hydroponic system myself but, I had to go with the less expensive generic peristaltic pumps (I saw that Mycodo supports these as well). So, I need help wiring my RPi 4, SainSmart 8 channel relay, 12V external power supply, and two 12V generic dosing pumps. If anyone out there has any info they can point me to, I'd appreciate it greatly!!

@ralphg I am using the Atlas Scientific dosing pumps. The thought was to try and use exactly was was in the post so that way there wouldn't be any compatibility issues.

Thanks for taking the time to comment. I hope you get a response to your flow meter wiring question.

The Atlas Scientific flow meter should be changed to I2C mode (per the manual), then you can connect the SDA and SCL pins to the I2C lines. Then just apply power, add the Atlas Scientific flow meter Input in Mycodo, activate the Input, and you should start to get flow data if water is flowing.

I'm working on this setup as well and new to working with DC power in general.  I have four Atlas pumps and one power supply.  Can the pumps be daisy-chained together to supply power?  Can someone post a picture of the backside of the dosing setup?  That's the one picture I can't seem to find and would explain a lot with how power was distributed between the singular power supply and the multiple pumps.  Thanks for a fantastic system!

I split my power to all of my pumps from a single barrel connector.

Thanks - figured it out and got that working, in addition to getting the EC probe running - just waiting on the lower EC calibration solutions to come in to start doing the dosing but already have 180 head growing in the system.