Will 5 X 5 vinyl fence post work as a nft.
If you are familiar with NFT, I believe this would be a good choice. I don't see any reason that it wouldn't. It is deeper than I prefer, but not to the point of ruling it out. Several people use vinyl gutter downspouts, which are 3" x 4". I personally use the open-topped gutters, filled with perlite, which are 4" x 5". Once you are comfortable with the science and mechanics of your system, you should use whatever is cheap and easy to work with.