Bulkheads on 300gal Stock tank?

[speedjester]

I brought a 1.1/2 bulkhead as pictured below. I was going to install the return 1/2” below the water line. My question is will it flow without a vent hole?

Thoughts? Very limited on place to mount bulkhead as the stock tank has curves and bracing.

 

[vtecintegra]

What do you mean by vent hole?

 

[speedjester]

What do you mean by vent hole?

My Dursa drains each have a vent on top. ( a small hole drilled above the elbow).