Anti siphon

[Mantani]

Setting up a tank I bought used. I replaced the bulkhead fittings in the bottom so I'm making a new siphon tube. The original had a t with u pick up off the side but the top was open. I assume just below the waterline as a siphon break? I see alot of u shaped tubes with a small tube coming out of the top. Is this the same thing?

 

[EeyoreIsMySpiritAnimal]

No. Those are Durso drainpipes (more trouble than they’re worth IMO).
The siphon break goes on the return line.

 

[Mantani]

No. Those are Durso drainpipes (more trouble than they’re worth IMO).
The siphon break goes on the return line.

Ok I'm confused now, the suction tube that was on my system was open on the top. The return line has a check valve at the pump to prevent back flow. Where on the return line would it go? And why was the old suction line open on the top? Picture of old vs new suction line