LOL, here is the info on liners-I have already confirmed the info for agriculture use with their customer service. You must get the agriculture defined plastic sheeting. This sheeting comes in lots of different widths, the links are for 8' but I see it also comes in 14' wide too. The thicker the liner the better.
This company has the black poly linked here
http://www.usplastic.com/catalog/ite...0736&catid=748
and clear(translucent) poly, also linked here
http://www.usplastic.com/catalog/ite...0732&catid=748
You can use a Koi pond liner if you have one, those liners are also food safe.
I also wanted to post an informational site on the different plastics available and the differences about what is food safe and what isn't. I was very confused on what type of liner was correct to use in the wicking bed design until I found this site.
http://www.rollitup.org/dwc-bubblepo...nightmare.html