The check valve does that, it is a miniature bilge pump and it has a fairly smooth delivery but what you describe is normal. You can switch to a duckbill checkvalve, both have advantages and disadvantages. The duckbill tends to be smoother running and less restrictive but the rubber hardens due to the kalk and only tends to last about a year. It is important with either one that the check valve is not the sole backflow preventer, the line should also be ziptied to the top of the dispenser.