Thank you Matthias - that helps.

I went through everything. I think the issue is the measurement cell not emptying after the test because when I flush the measurement cell and test again it seems better. Also that 3rd dosing pump makes a lot of noise.

I am just going to decrease the calibration ml/min from 35 (to 30 I did but didn't work) to 17.5 and see how that works.

Let's see how this goes