Hydronic heat flow question?

i am about to hook up my in floor radiant heat system. there are 5, 100 foot loops that go thru the slab. i made the manafold myself, and when i tested it for leaks it seemd like the first fitting closest to the feed direction had the most flow, then less and less till the last one. a freind sugested hooking up the first feed to the last return? kind of mixing up the tubes to make a beeter mix? any thoughts on this would be great. thanks john