need help with noisy pipes please

[lastlight]

Both pipes are gravity fed and 1 inch bulkheads and pipes. I'm barely putting any water into these and they seem to gurgle a lot as is. I'd like to have a bit more water drain through them and silently.



Green pipe is a bulkhead to a 90 and straight down into my sump. blue one makes a right turn in a 90 and then wraps around my skimmer before a 90 down into my sump. Both drain ends are submerged.

It seems with only a trickle entering my fuge (blue line), the water level will still climb to the top of the bulkhead and then every few minutes it will pull a vortex of air from the surface and drop before slowly rising again.

So what will help me here? The flow is so slight as it is I know 1" can handle far more than I'm feeding these drains. Have the ends not submerged? Drill a hole in the tops of the bulkhead 90s to let some air in? I think the air-tightness of the drains may be my problem but I'm unsure.

Thanks!