Intermittent EZO-PMP Volume Dispensing

We initially purchased four Atlas-Scientific EZO-PMP devices for use in a hydroponic automated dosing system, similar to what Kyle Gabriel built and was kind enough to share. While all pumps were initially working great, one is now behaving oddly.

When we send a command to dispense a volume of liquid in Mycodo (version 8.12.8), the pump only dispenses a small amount and then continues to quickly shut on and off approximately every 30 seconds, dispensing a small amount of liquid each time. Mycodo reports that the command was sent successfully. All other commands, such as a set time for dispensing the liquid, work as expected. All three of the other EZO-PMPs, connected over the same i2c network, do not display this intermittent volume dispensing behavior. We recently completely replaced the problematic EZO-PMP with a brand new pump and connector cable but the problem still persists.

I’ve tried everything I could think of to debug this, including isolating the i2c network to just the problematic pump and running the pump off it’s own 12V supply. I initially thought that the pump went bad, but now doubt that as it’s been replaced by a brand new unit. I would like to see exactly what commands are being sent from Mycodo for the faulty pump vs working ones, but I’m not entirely sure where this is logged.

Has anyone else experienced this problem before? I really appreciate any suggestions to help me debug this strange issue.


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Hi. It sounds like you have configured it to dispense at a slower rate. Try deleting the output and creating a new one to ensure you are using the default settings (fastest rate).

If you enable the Log Level: Debug option you can see the commands being sent to the pump.

I deleted the output and added a new one for the pump and now it’s working again! Not sure how the configuration got changed to dispense at a slower rate, but at least it’s working now. Thanks so much Kyle!

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