Determining FLOW RATE with simple hall effect flow meter

Can anyone help me with calculating water flow rate with a simple hall effect flow meter?

I am building a hydroponic monitoring system for my garden. It monitors 3 temps tank, return water from the beds, air, has a float sensor for the nutrient tank level and then a flow sensor. These 5 sensors will sound an alarm if outside of the set limits. If the pump fails or partially plugs up the flow meter will catch the lack of proper flow and sound an alarm. My pump failed this summer and I lost most of my squash plants.

I tried lots of ways I could think of such as using digital read, clock and counter and reset them through a defer after various lengths of time. Each time the time counter resets you get a momentary 0 which causes an alarm due to 0 “zero” flow and totally inaccurate flow rate.
I have the “wayland/sfm3x00-flow-meter” library however I believe this library is for a medical flow meter and I could not find a way to make it work on my flow meter.


You could ignore flow reading when start time > end time to avoid the false zero reading.

In your case, it doesn’t sound like you care about actual flow volume over time, you just need to know if the pump is still working, so checking flow rate “right now” without worrying about integrating over time should be enough.

You might also be able to avoid the flow rate meter by using another float to check water level flowing into the system.

Thanks gweimer for your reply.

Your instinct is mostly correct as I don’t care about an accurate flow reading. I would like to have a reasonable rate. If the pump is partially blocked and flow is reduced then I would not receive water to the farthest dutch bucket. Each bucket is filled with gravel, has a drain and a 1/4" feeder tube. If the pump is running at reduced flow some buckets don’t receive any water. I need enough accuracy to make this determination and sound an alarm but, I don’t have to have the exact GPM.
I greatly appreciate any help!