Seedling yellowing

[Hydro_]

I popped Zkittles auto and over the last two days the bottom leaves began to yellow rapidly. In the past I just sprout them in the rockwool then transfer to DWC at the third set of true leaves. My setup:

4x4x6'6" tent
8" inline, pulls air in through the floor level vents, exhaust through side near top. Low setting
Two 230watt COB led (actuall draw is about 230 watts each)
Light cycle 18/6
Water is tap, just a bit in the bottom of the seedling tray
roots are exiting the bottom of the cube, healthy/white

Pics for reference, any suggestions will help. Thanks for your time.

 

[Ganoderma]

The reason it's yellowing is because it needs nutrients/food. Once you start feeding it, you'll see it start to perk up.

 

[Hydro_]

The reason it's yellowing is because it needs nutrients/food. Once you start feeding it, you'll see it start to perk up.

Right on. I transferred it to a little DWC bucket at 250ppm with flora 3 part. Will update.

 

[Creeperpark]

I would use all 3 parts equaling about 250ppm to start with. If you are lacking Micro and Grow, you will have minimum amount of nitrogen. Try to always use all 3 parts in the beginning to get the best out of the flora series.