Need help.

I had this problem two years ago so i didnt plant this garden last year....decided to plant it again and low and behold i am having the same problem. Ocean Forest soil, 150 gallon smart pots. I've hit them with max sea, cal mag, liquid karma, sea green, a grow nute made locally and even tried compost tea.....All of these were not used at once just over a period of time. Ph is at 7 which i know isnt ideal but has worked fine before. The veins in the leaves turn brown and eventually kill the leaf...starting from the inside of the plant and moving its way out.any info would be greatly appreciated.