Brown/black colored lettuce leaves
I thought I posted this, but don't see my post... sorry if it shows up as a dupe...
Attached is a picture of my NFT bibb lettuce.. it has some brown/blackish color to the leaves.
It has been in the NFT system for about a week, after spending a week in the nursery channel (flooded channel, basically).
PH is 6.2, just lowered to 6.0
Water is 200ppm (ec x 500 scale), added nutrients to about 1150 now.
Temps are in the mid 70's (air and water).