If I understand you correctly, you are 40 days into flower. If so, your plants look completly normal for many varieties. It is very common for leaves to yellow during this time. It is the plants last effort to put every bit of energy it has into making the buds. That's it's lifes goal, so it is actually eating parts of itself that are not as important as the buds are. There is nothing you can do about it.

And welcome.
Opie Yutts Reviewed by Opie Yutts on . first grow (nft), problems Hello I am new in this forum, you pardon my English because I am Spanish, to question: it is my first culture in nft, to cultivate 12 clones ww and 4 of sherezade, in growth the plants to grow very well, beginnings of equal flowering, but to the 20 days of flowering they begin to deteriorate the leaf and not to create dwell flowers, the pump 1000L/H =16L/M, after the plants many roots the level of the water to raise flooding the roots completely, can be that the problem of my plants? Every 2 Rating: 5