yellowing leaves

hi all
most of the lowest leaves are yellow
i use DWC with 3 part GH flora

Lower leaves tend to get yellow when they get shaded out from higher leaves. You could get some calcium nitrate if you want them greener though.

A picture of the whole plant helps a lot! One leaf does not show the whole problem.

here some pics

so?
any help

Is new growth green and healthy? If so, I wouldn't worry about it too much, especially if they are low, old, and down in the shade.

If the yellowing is progressing up your plant I would imagine it's hungry. What is your ppm or ec?

It could also be a ph issue, have you been staying on top of monitoring it?