Why do air bubbles form in the dosing pump when dosing zeostart?

[esco]

Hello
I want to use my ghl doser 2.1 with zeostart. I tried and saw that zeostart makes bubbles inntube always. Dosing cal and kh with this pump but both never makes any bubles. Only bubbles when tring to dose zeostart. Why is this happening?

[G.Alexander]

I have never had this issue and never hear someone else has observed it. Have you already tried a different channel of your pump and a new hose ?

G.Alexander