Well this hasn't gone aswell as i'd hoped

Been trying to get the irrigation working in my spare time, but it's been a nightmare.

Firstly the kit I have doesnt come with elbows, so I ordered some off Amazon. But it appears I have a 1/4" US system and everything on Amazon UK is metric 4-6mm. The elbows just pop off when the water is turned on as they are too small. I then ordered some from Amazon US marked as 1/4", but even they were too small. Fortunately returning with Amazon has been painless.

Giving up on the elbows I just used the Tee connectors that came with the system, blocking off one outlet to form an Elbow.

However, now I've fired up the system I can't get it flowing properly. It starts to work, but then after a couple of rows air starts to come in from one of the higher drippers Here's a video to demonstrate:

https://www.dropbox.com/s/5mawc28qhz...%2053.mov?dl=0

Where am I going wrong. Should I have run it from the bottom up instead?

My thumbs are sore at this point, so thought I'd seek advice before putting them through any more pain.