NFT Help!!

I'm in the middle of a DIY aero/nft build. I've run into some problems though and was hoping an experienced NFT grower could answer a few of my questions.

I'm using 4"x4"x6' vinyl fence posts as my troughs and wasn't sure what the pitch should be.

I was also wondering how many gph are needed to make the most effective film in just one of the fence posts.

Any advice would save me a lot of time and money +rep I'd greatly appreciate it.

read this https://www.rollitup.org/hydroponics-aeroponics/116859-harvest-pound-every-three-weeks.html

edit^ he starts with the clone but read into it a little and he explains his aero/nft flowering system

Thnx 4 the help