Where should the drain in a loop go?

[Anniemay]

Hey guys. Might seem like a bit of a noobish question but I am about to do a new build and was wondering something. During my research before doing my first water cooling loop I remember reading somewhere that the drain should be in a certain location in regards to the pump, either before or after. Of course I am now looking for that page and I'll be damned if I can find it. I remember that the article mentioned something about causing issues with relation to the flow if it was in a certain position. I know that the drain should be coming off the lowest point in the loop but is it better to put the drain upstream (before) or downstream (after) the pump? Thanks in advance for the help guys.

[WrigleyVillain]

I've only ever heard "lowest point" but I guess I would put it after the pump. I really don't see how it matters offhand; the system is off and just uses gravity to drain.

[Anniemay]

The way that I understand it is that the location of the Tee that would lead to the drain can cause some flow issues while the system is running if it is put in the wrong location. Might be wrong but wanted to make sure before I started.

[GliderHR]

Hi,
How is the weather over there? :)
Nevertheless, I have my drainpionts behind the pump on the bottom of the case. I attach some pictures.
System 1
http://s7.directupload.net/images/user/140124/pus8wmbg.jpg
System 2
http://s14.directupload.net/images/user/140124/w93kmeuz.jpg
http://s14.directupload.net/images/user/140124/si36caeh.jpg