Bubbles going backwards always mean a leak?

First year on vacuum. I used bags last year.

10 taps on 5/16 line and flat surface with surflow vacuum pump. There is a vacuum gauge before the pump, and the pump simply empties into a large bucket.

Sometimes I notice the bubbles going backwards (away from pump) and then they will reverse direction. Does this mean I have a leak somewhere?

I run the pump 24/7 (even when below freezing) and have a 60w bulb in the container to try to keep things from freezing. The container is not insulated. I'll probably switch to a cooler next year to better protect it.

Here's a video showing a possible leak at the T before the pump.

https://youtube.com/shorts/y-5kN7K796U?feature=share

I've never seen the bubbles go backwards. Do you have a recirculating loop on the pump? To do that, just run a single line from the output of the pump back to the input. That helps keep the vacuum higher, a dry diaphragm doesn't get very good vacuum. In the 5/16 recirculation line, add a needle valve if you can and adjust it to just allow a little sap to go back to the pump inlet. Another option is to use 3/16 tubing for the recirculation line, but you would likely need to find a local producer who uses 3/16, it's sold in like 800' coils.