View Full Version : 2.1 dosing pump in reverse mode, issues.

06/18/2017, 08:17 AM
I have a refrigerated dosing unit, with 3 stir plates that I run for my nps systems. I run them forward for 80 ml and then reverse for 60 ml. This would dose my tank 20 ml of food. (All figures are hypothetical). We calibrated all pumps to measure how many ml of liquid it took to get to the edge of the water line.
Except what happens is that when it runs in reverse mode, it floods my dosing container. Which leads me to believe that it's a calibration issue when run in reverse. Is there a way to calibrate a pump in reverse?
The other possibility is that I am getting a Venturi and it's back siphoning into the fridge. I need to keep both ends of the tube submerged and it's physically impossible to move the fridge to be level with the tank, so if it is a backsiphon, I'm going to have to find a way to put an air release or air valve along the line somehow (can't use a check valve as the line has to be able to draw backwards)

Second issue, I have the stir plates set up to come on 10 seconds ahead of the pump and quit when the pump comes on. This doesn't always happen. Sometimes the stir plates come on and stay on for the entire time the pump is running. It seems to be the same pump head that overfills the dosing container.
So I'm wondering if there is an issue with communication.
Looking for ways to isolate the issue in order to resolve.