Had that happen to me as well. what I did to stop that was to fill my DC carto up, then put it in the UFS and make sure the juice and air are turned off. Then I fill the UFS tank to halfway between the top of the clear window threads and the very top threads of the UFS itself. I then put on the top cover, top cap, and my Ming tip. I can go quite a while on the juice in the carto before I have to open the UFS juice control. When it's time to do that, I typically open it all the way. Air control is usually about 3/4 of the way open.
Don't typically get any gugrles but if I do I close the juice all the way and vape it till it needs more juice, then repeat.