This is why my gravity-fed rainwater hose does not always water my garden, which is about the same level of my cistern but travels via a dip midway (I figured t

This is why my gravity-fed rainwater hose does not always water my garden, which is about the same level of my cistern but travels via a dip midway (I figured the dip would remove bubbles once filled with water, but I was wrong...not sure how bubbles form: bacteria? Out gassing of warmed water). Very frustrating. I use a valve to bleed water near the dip by turning the valve on and off to hammer out the bubbles. Takes forever and I'd like it to be automatic (because I want my rain water cistern to overflow to my garden too. But I don't want to get rid of the bubbles by going outside in the rain, or going outside at night)